Snail Farming
Snail Farming
Snail farming, also known as heliculture, is the process of raising land snails for food or other purposes by humans. Generally, their flesh can be used as edible escargot, their slime in cosmetics, and their eggs for human consumption as a type of caviar.
Snails belong to a molluscan class Gastropoda, that has a coiled shell large enough for the animal to retract completely into. But when snails are being referred to, the focus isn’t only on land snails, but also on thousands of species of sea snails and freshwater snails.
The purpose of this article is to focus on land snails because they’re the most widely used for snail farming.
Business Opportunities in Snail Farming Around the World
Food Consumption
Edible snails are a part of regular meals in most households around the world. In Nigeria for instance, many homes prepare their soups with snails occasionally. Despite the infrequent use of snails in meal preparations in the country, the demand still exceeds the supply. This want doesn’t just show a large snail-farming business opportunity in the country, but also shows the large potential in exports outside the country.
A short list of some countries that consume edible snails includes Spain, Nigeria, Algeria, Cameroon, France, Cyprus, Ghana, Malta, Italy, Vietnam, Laos, Cambodia, Terai of Nepal, southwestern China, and several parts of the United States.
As long as people will continue to demand snails in their meals, it will constantly remain a lucrative business opportunity for agribusiness entrepreneurs to take advantage of.
Cosmetics
Snails have great uses in the cosmetic industry. Different skin creams are gotten from the Helix Aspersa, and can be used in treating scars, acne, wrinkles, and dry skin. The secretions from the Helix Aspersa under stress, can be used in the regeneration of wounded tissue.
Benefits of Snail Farming
- Easy to handle.
- Shells can be used for ornaments.
- Less land for cultivation.
- They’re cheap and easy to raise.
- Not capital intensive.
- Snail Meat contains anti-tuberculosis attributes.
- Snail meat is used in the production of local herbs to be used by pregnant women.
- Snail farming can be done part time.
- Snail farming can be done alongside grasscutter farming.
- And many other benefits.
Breeds
The Suitable Snail Species for Snail Farming
Achatina Fulica
This African land snail is largely located in East Africa, especially Kenya and Tanzania, and has the scientific name Achatina Fulica. They are famously known as the “giant African snail” or the “giant African land snail”.
Although they’re largely found in East Africa, these snails are can also be found in the US, China, Taiwan, and India. The adult Achatina Fulica snail is usually around 7 centimetres (2.8 in) in height and 20 centimetres (7.9 in) or more in length.
The shells of these snails are conical in shape, and also about twice as high as it is broad. The colours of their shells highly vary because they depend largely on their diet, but brown is the most common colour of these African land snails.
The major downside of the Achatina Fulica is they’re a large cause of pest issues around the world.
Achatina Achatina
Also known as the “African tiger land snail” or the “African giant snail”, these species of snails are air-breathing land snails. They are said to be largely located in West Africa, between 160 to 300 kilometres off the coast of countries like Nigeria, Ivory Coast, Benin, Sierra Leone, Ghana, Liberia, and Togo.
The shells of the Achatina Achatina can grow to a length of 18 centimetres (7.1 in) with a diameter of 9 centimetres (3.5 in). Some have been observed in the wild to grow to 30×15 cm. These measurements make them the largest extant species of land snails.
The Achatina Achatina is a great source of protein. They are hermaphrodites just like almost all pulmonate gastropods, and have both male and female organs. This makes each snail able to lay up to 1,200 eggs in a year. The downside of the Achatina Achatina is they can be serious pests, and cause adverse effects to agriculture, natural ecosystems, commerce, and human health.
Archachatina Marginata
The Archachatina Marginata are giant West African snails or Banana Rasp snails. They are air-breathing tropical land snails, can grow up to 20 cm long, and have the ability to live for up to 10 years. This species of land snails is majorly found in Nigeria, through Cameroon, the Republic of Congo, the Caribbean, and Martinique.
These snails are nocturnal forest dwellers, and dislike overcrowding. If they get too crowded in a particular space, they begin to spread out.
Their mating method varies per location. Because they do not have both sexual organs, they have to mate with the opposite sex to reproduce. This mating method makes reproduction and population increase very slow for the Archachatina Marginata, unlike the Achatina Achatina.
These land snails eat plants at a ferocious state, and so, this behaviour leads to the destruction of crops and damages to homes. This is one of the strongest reasons the Archachatina Marginata are banned in the United States.
Types of Land Snails
Giant African Land Snail – Achatina fulica
The Giant African Snail is a 20 cm long snail native to Africa, and it is one of the largest snail species. In some places, it is considered an invasive animal because of its high reproduction rate and voracious appetite for crops and vegetation.
The garden snail is a small species with a height up to 1.3 inches and a particular shell design that distinguishes it from other species. They are native to the Mediterranean region, Western Europe, part of Asia and northern Egypt.
The Roman snail has a beautiful shell that is almost a third of its total weight. Originally native to Europe, it is found in most of the world now. It inhabits in temperate forests with humid temperatures but scanty rainfall.
Housing
Snail Housing Construction
The type and dimension of your snail housing (also called snailery, or snail pen), depend largely on the snail growing system you choose, and on the quantity of snails you intend to produce. The age of snail, temperature, location, weather conditions, and flooding vulnerability of your snail farm, are all factors to consider.
As management activities and level of financial inputs differ from one farmer to another, snail housing also differs in size and capacity. Snail housing system can be classified into three categories: intensive, semi-intensive, and extensive.
Intensive snail housing system: This system of snail housing tries to recreate the natural habitat of snails. Plastic tunnel houses, greenhouses, free-range snail pens and buildings with controlled climate fall under this category. This system is usually practiced by farmers who do snail farming business for commercial purposes, and occupy large expanse of land.
Mixed, or semi-intensive snail housing system: In this system, egg laying and hatching occur in a controlled environment. The young snails are then removed after 6-8 weeks to outside snail house for further development and growth.
Extensive snail housing system: Practiced mostly by small scale farmers and subsistence farmers (mainly for consumption). Snail farming in this system is done using relatively cheap and readily available materials like, old car tyres, baskets, old tanks or drums, pots, etc.
Characteristics of a Good Snail Housing
Your snail housing must have enough space for your snails to graze freely. Overcrowding your snailery impedes the development of snails and therefore should be avoided. A well-spaced snail housing reduces the risk of disease outbreak caused by overcrowding.
Good snail housing should be able to protect snails against predators, poachers, and insect infestation. predators feed on young snails whereas poachers steal snails. As for insects, they lay their eggs on the snails: these eggs develop to the larvae stage, and then feed on the snails from inside their shells, thereby causing high snail mortality leading to loss of investment.
It must be easily accessible for carrying out management activities. Snail housing should be built in such a way as to enable managers handle snails, place feed, carry out cleaning activities and other tasks.
The snail housing must prevent snails from escaping. No matter how slow snails can be, they can still wander off through open spaces and invade your house or garden. Therefore, all possible snail escape routes should be tightly closed.
A snail housing must be well ventilated and provided with adequate shade.
An adequate snail housing must be able to protect the snails from excessive wind. Wind increases the rate of moisture loss in snail which in turn, leads to dryness for the animal. Planting (fruit) trees around snail pens will help to reduce wind speed and improve the micro-climate. It will also protect the snails from scorching sun or torrential rain.
Snail Housing Materials
Depending on price and availability, the following materials can be used as snail housing materials; Concrete blocks or bricks, polythene sheets, galvanized sheets, Mosquito nets or nylon mesh, and chicken wire. Decay and termite resistant timber play important role in the construction of snail housing. In West Africa, favourable tree species that produce such timber include opepe, iroko, and mahogany. Disposable materials like car tyres, baskets, oil drums, and old water tanks are also good materials.
Types of Snail Housing
Baskets
Baskets are used for raising hatchlings of less than three months of age or for incubation of eggs. The major limitation in the use of basket for raising snail is poor durability.
To make snail housing using baskets, the following procedures should be followed.
Get a good basket and lay sack on the bottom to hold soil.
Fill the basket with humus or loamy soil to a depth of 15-20cm.
Put dry leaves on the soil for mulching.
After that, cover the basket with a lid, or chicken wire mesh placed between two mosquito nets and fastened with a wooden frame, to provide protection against insects.
Hutch boxes
These are square or rectangular, single, or multi-chamber wooden boxes with lids, placed on wooden stands. Hutch boxes are useful in semi-intensive snail breeding system. They are very suitable as hatchery and nursery pens because eggs and young snails can be easily located and observed.
Steps involved in the construction of a hutch box
The dimension should be about 100cm x 100cm x 50cm with a stand of 35cm.
The box will have cubical wooden frame.
The base of the box should be built of hard wood and perforated to allow free drainage of excess water.
After constructing the box, sieve humus or loamy soil into it to a depth of 20 – 25cm.
Cover the box with a lid made of chicken wire mesh reinforced with mosquito nets. The lid should be fitted with a padlock to discourage poachers from stealing your snails.
The stands of the cage which is 35cm high should be placed inside a container or bowl filled with water plus kerosene, used engine oil or any other disinfectants. This will prevent insects from crawling up the box.
The soil in the hutch box must be changed occasionally because an accumulation of droppings and slime will increase the chances of disease development.
A box of 1sqr.m can be used to rear 4 – 6 mature snails.
Advantages and Disadvantages
A major advantage of hutch boxes is that they can be placed close to the farmer’s house, ensuring good supervision and protection. The height of the hutch boxes makes them comfortable to work on and facilitates feeding and handling of the snails.
In contrast, hutch boxes are somewhat expensive to construct, and they come in limited sizes, which restrict the number of snails that can be kept in them.
Old tyres
Old tyres are less expensive and readily available in urban areas. However, tyres have poor ventilation. You can improve ventilation by perforating tyres using a hot pointed metal rod.
To constructs snail housing using old tyres,
Select an appropriate site under a shade.
Stack 3 – 4 tyres upon one another.
After stacking, fill the tyres with suitable loamy soil to a depth of 10 – 15cm.
Cover the tyres with chicken wire and mosquito mesh, placed between the topmost tyre and the second one from the top for protection.
Car tyres can hold up to 3 – 6 snails, depending on their sizes. Tyres of larger diameters can hold between 5 – 10 mature snails.
Drums/Old Tanks
Oil drums and old tanks could also be used to raise snails instead of discarding them. Old tank drums are good for small-scale production (especially for family consumption).
To construct snail housing using oil drums or old tanks;
Perforate
Lay sack on the bottom of the tank to hold the soil and then fill with humus or loamy soil to a depth of 10-15cm.
Place dry leaves on the soil layer as mulching.
Cover the box with a lid made of chicken wire mesh reinforced with mosquito nets.
The tank could be placed on a stand if available.
Trench Pen
To construct trench pens,
Select an appropriate site and peg out the position of your pen.
The trench is either dug into the ground or raised 40 – 50cm above ground level using cement blocks.
Ensure that the trench is well drained to prevent water-logging
Fill the trench with good loamy soil to a depth of 10 – 15cm.
Concrete can be leveled on the floor of the trench before topping with the soil.
Construct feeding and water trough to a height 5 –7cm above the soil level.
After that, cover the pen properly with a well fitted framework of chicken wire plus mosquito net.
Trench pens have the advantage of being flexible, especially when sorting snails according to their sizes and phase in the growing cycle. The snails are always easy to locate, for handling, feeding, selection and final sale or consumption. On the contrary, trench pens have the disadvantage of being expensive to construct (especially the raised trench pen). Secondly, the farmer may end up having backache because of long stooping or kneeling due to the low height of the trench.
Free-range snail farming
Free-range snail farming is where snails roam freely and feed on open pastures of living food crops, rather than being densely confined in small enclosures and fed only compound foods.
The freedom to roam in large areas allows the snails to avoid each other’s slime trails. Over-slimed ground and excess faeces can change snail behaviour by putting out chemical signals like *pheromones which are detrimental to reproduction and growth rates in snails.
* A pheromone is a chemical an animal produces which changes the behavior of another animal of the same species.
Allowing snails to breed at their own pace and encouraging the natural biological cycle in an ecological farming system, results in better breeding performance, faster rate of growth, higher reproduction yields and it meets the highest standards of quality and sustainable accountability.
The free-range snail housing system however, has its own disadvantages.
It requires more land than other types of snail farming.
It is difficult to locate and protect eggs and small snails.
A fully enclosed and roofed pen is relatively expensive to build.
In the open type of free-range pen, it is more difficult to keep out predators and poachers.
It may be difficult to control disease outbreak because of the farm size.
Feeding and Watering
Most snails eat a wide variety of food, some species more than others. Most fruit and vegetables will be taken. Certain ‘hard’ vegetables like carrot and potato benefit from being slightly parboiled and allowed to cool down completely before being given to the snails.
They also like tortoise food – either dry or soaked in water. If you live in an area where you’re likely to be snowed in in the winter, it’s handy to keep a jar of this stuff for emergencies – it keeps for ages, and the snails don’t mind it one bit! They will also eat raw meat like mince.
Snails also like a drop of beer, they are attracted by the yeast and it is actually quite good for them, in small amounts.
Water isn’t necessary for the snails as long as their surroundings are humid enough, a bowl of water is recommended as the snails will drink from it and also like to ‘bathe’ in it. The heavier the bowl the better as they will tend to tip it up! It must also be shallow so they can’t drown. You do not have to provide drinking water – as long as you keep the snails damp, by spraying with (warm in winter!) water about twice a day, depending on how quickly your substrate dries out, they’ll get all the moisture they need from this and their food, but they do appreciate a small bowl of it in their tank. (If you’re using a heat mat, remember the substrate will dry out much faster, so you’ll need to ‘water’ your snails more often). Little rock-effect drinking bowls that are sold in reptile shops are ideal; they are graduated so that your snail will not drown, and flat so the snails will not tip them up. For more information on suitable water dishes click here.
You need to provide fresh food and water every day or possibly every other day if the food doesn’t spoil quickly. Don’t leave spoiled food in the tank because the environment in the tank will encourage mold and fungus to grow and will attract other pests such as flies and mites. If you are having this problem click here.
Important: You MUST wash all food and forms of calcium before they are offered to the snails.
Calcium
Snails MUST have a plentiful supply of calcium to build and repair their shells. Keep a piece of cuttlefish bone in their tank at all times. Cuttlefish bones are cheap, costing between 20p and £1 per bone and can be found at just about any pet supplies store. It’s worth buying them in bulk because they are cheaper that way.
Keep a washed cuttlefish bone in the tank and you will see them rasping away at it. Large, growing snails can demolish it in no time. Other sources of calcium include: egg shell, calcium supplements from pets’ shops, oyster shells, natural chalk and baby milk powder.
You may find that cuttlefish begins to go soft and slimy. To slow this down I recommend a number of things. Firstly, putting the cuttlefish on a small plastic tray or piece of polystyrene (like the bottom of a foam cup) the cuttlefish bone won’t get damp from underneath.
Breaking the cuttlefish bone up into a few pieces and supplying what they need obviously prolongs the life of your cuttlefish because it’s not all left in a humid tank. It is important to leave enough in the tank for them at all times and if the pieces are smaller, enough for all of them to get close enough to eat them. A few babies in a tank would take months to consume a full cuttlefish bone so using a full one is unnecessary.
Swapping the pieces every few days and rinsing and drying the old ones helps a lot. Over time the bones will become very brittle but they will last a lot longer. Having said all the above, don’t be stingy with calcium. The points above are just tips to prevent it being wasted.
Snails can also absorb calcium through their foot and you may witness your snails sitting on pieces of cuttlefish.
Too much calcium can result in internal stones that can be harmful. If you’re feeding as part of a mix, the recommended amount of calcium is 12% for optimum health and growth, although one study showed 20% to best. However, it is likely the speed of growth was more important in that study than the snails’ health. What is does show is that up to 20% is likely to be safe.
There are alternatives to cuttlefish they may accept
Calcium Supplements
You can buy calcium powders and liquids from pet shops. It costs about £3 (€4.40) I’m not sure how economical it is compared with cuttlefish, but if you actually powder one yourself, you realise how little powder that produces. It may even be cheaper. What remains to be known is whether other sources contain other shell building substances that snails can use.
Powdered Oyster Shells
Unfortunately, I haven’t been able to get it in powdered form, only crushed which is of no use as pieces larger than powder are way too hard and sharp. It was used in this study and was found to be the best source of calcium out of the ones tested, perhaps because it is 99% Calcium carbonate as oppose to 80-85% in cuttlefish bones. If powdered costs the same as crushed, then it much cheaper than the cheapest cuttlefish bone I have found. Update: I have found some finely powdered oyster shell and the snails absolutely love it. Not as fine as I’d hoped but much finer than the bird grit you get from pet shops. They tend to pass large amounts of it out but they prefer it to cuttlefish if both are presented.
Natural Chalk
A good source of calcium. I don’t know where to obtain it and I imagine it is expensive.
Dolomite
Click here to learn what it is. You’ll see it mentioned on snail farming websites. Where you obtain it from I have no idea. I assume it is powdered before use because snail farms make a mix. Update. Dolomite is an unsuitable type of calcium because it is containing magnesium which retards calcium absorption.
Limestone
You should be careful not to mistake this for lime which is caustic. The natural rock is what you need. Where you get this from I don’t know.
Egg Shells
Remove the inside skin, and wash the eggs thoroughly. If you wish to crush it, you may find baking the shell in the oven makes it more brittle. Not a particularly good source but better than nothing if your snails won’t try the other sources of calcium.
Wood-ash
Used in this study, although it was found to be the least effective source of calcium. However, if you have a snail refusing other forms of calcium I would say it is worth a go. I don’t know where you could get it from.
Bone Meal
Used in this study. Bone meal is used as a plant fertiliser so you must be careful that what you get hasn’t got added chemicals. I thought about trying this but decided against it, until I know more.
Update: “Bone meal is not recommended, as it may contain contaminants” – Taken from www.osteoporosis.ca.
I realise this info is targeted at osteoporosis sufferers but it does seem to indicate the possible presence of contaminants. Although the aforementioned study itself reported no deaths it seems likely that these contaminants are harmful to snails. It just doesn’t seem to be worth the risk unless you can guarantee a “pure” supply, if such a thing exists.
Food Lists
The list below shows some of the foods they will eat. This is not a comprehensive guide; all snails have different tastes even within species that are not known for eating a particular substance. Try different foods out, if they don’t like it they won’t eat it. In the wild snails probably eat whatever they can get and in doing so probably have a mixed diet. It seems reasonable that this should be emulated. If your snail seems to only eat apple, it is more than likely because it is always on offer. It may not necessarily dislike other foods.
Note: Raw food has a higher nutritional content than cooked or processed foods.
Fruit: Apple, Apricot, Avocado, Banana, Blackberry, Butternut Squash, Dragon Fruit, Grapes, Kiwi, Mango, Melon, Nectarines, Orange, Papaya/Paw-paw, Prickly pear, Peach, Pear, Physalis, Plum, Raspberry, Satsuma, Sharon fruit, Strawberry, Tomato
Vegetables: Aubergine, Bean Sprouts, Broccoli, Cabbage, Carrot, Cauliflower, Courgette, Cucumber, Green beans, Kale, Leek, Lettuce, Mushroom, Parsnip, Peas, Potato, Pumpkin, Spinach, Sprouts, Swede, Sweet Corn, Sweet Potato, Turnip, Watercress, Dandelion leaves, Common Plantain.
Other: Hemp, sunflower seeds, pumpkin seeds, oats, chicken mash (for laying hens), Snail Mix, Oats and other seeds need to be soaked first. Seeds are best served crushed or ground. Raw eggs, brown bread, milk powder, some raw meat. Wet or dry cat treats/dog biscuits, tortoise food.
For a list of plants African snails have been found on in the wild click here.
For a list of the calcium content of various fruit and vegetables click here.
Dangerous Foods
Foods that that may have been treated with pesticide or contaminated by vehicle fumes, e.g. home-grown fruit and vegetables and dandelions.
Millet and Pasta can cause bloating (water-retention) through internal blockages and can result in the death of a snail. I’d avoid overly starchy foods, like rice also. These foods seem largely indigestible.
Salty foods – like most animals, snails do need small amount of salt to survive but salt is obviously dangerous in anything but tiny amounts.
There has been some discussion on the Cyber snail mailing list regarding high amounts of oxalates in certain foods like spinach. There is some concern because:
“…Oxalic acids bind with needed nutrients and pretty much makes the needed nutrients inaccessible to the body. The main nutrient that seems to be depleted is calcium…” (Taken from: http://www.iguanaden.com/diet/oxalic.htm – link dead)
However, snails may actually be able to detect oxalates and avoid plants that contain high amounts of them:
“…and a land snail Eremina desertorum. All three species eat only those parts of the leaves where calcium oxalate raphides are absent, suggesting that it is an effective defensive chemical.” (Taken from: http://springerlink.metapress.com/app/home/contribution.asp?wasp=dfdq68fqupcxxjd18g8h&referrer=parent&backto=issue,7,20;journal,96,97;linkingpublicationresults,1:104273,1 – link dead).
A mixed diet would seem to be the best solution, feeding foods that are particularly high in oxalates sparingly.
For more information on oxalates click here.
For a list of the comparative oxalate content in vegetables click here.
There are some people who think that particularly acidic foods like citrus fruits can be bad for snails. However, there are pictures on the web of snails being fed on oranges, tangerines, satsumas etc., so the jury is out really. Not to mention that apples, tomatoes and kiwi fruit are also acidic. Similar to above, it may be that excessive amounts of acidic food can be detrimental to the snails’ health. As always, it is best to err on the side of caution and be less generous with particularly acidic foods. With a good variety of food on offer, the snails will not suffer any ill-effects.
The most common cause for shell deformation is a temporary arrest in the shell growth. Due to circumstances (lack of food, lower temperatures) an apple snail can stop growing. This doesn’t always mean that the snail is in bad condition or that one should change the environmental conditions. Once the snail reaches a certain size, depending on species and circumstances, it starts using its energy for reproduction efforts instead of growth.
Problems regarding shell growth often start when the temperature suddenly increases in combination with an abundance of food or when the water quality changes (after a large water change). The snail then switches back to the growth stadium and stops with the reproduction efforts. This should not necessarily be a problem, but when the growth line of the mantle edge (were new shell material is made) is damaged the situation changes. Damage in the growth line is often induced by the mating behaviour, when the snails mount each other and the borders of their shell clash. Once the shell grows again, the damaged parts stay behind in growth and an irregular shell border arises. In many occasions, the snail manages to overcome this problem (figure 1), but sometimes the damage can be lethal (figure 2). Besides growth problems due to a damage at the shell-forming tissue near the shell opening, some apple snail species can grow a large, expanding aperture when they reach adulthood, giving them a somewhat trumpet-like shell opening. Especially the male snails develop this appearance, probably as a result of their space occupying penial complex. Such growth should of course not be considered abnormal. To prevent shell grow problems; it’s best to avoid sudden changes in the water/food conditions. Always try to keep these factors as constant as possible.
Once a growth problem occurs, it can be quite hard to help the snail. Probably the best thing to do is to slow the growth of the snail down by reducing the amount of food somewhat (don’t starve the snail) and by lowering the temperature with a few degrees. Once you see that the snail is able to solve the problem, you can choose to elevate the food supply and increase the temperature or you can choose to keep the current conditions. The latter option is attractive if the conditions are still within the optimal way to keep the snails healthy and when your snails have matured enough, so further growth is not desired.
Irregular growth of the operculum
| Figure 4.
Irregular growth of the operculum. |
Problems with the growth of the operculum have a similar cause as the shell growth problems. Very important is the tissue of the snail that aligns the operculum at the inside. If one sees this tissue retracting, there could be a problem with the snail, although is normal in older snails in which the growths has slowed down or even halted.
Discoloration in new shell
The pigments that determine the colour of the shell are mainly located in to organic outer layer (periostracum) of the shell. The speed at which a snail grows largely determines the thickness of the periostracum. At slow growth speeds, a relatively thick periostracum is formed, while a high growth speed results in a thin, more transparant periostracum. It’s not difficult to imagine that a thicker periostracum also results in a more intense and darker colour of the shell. It also explains why wild caught snails are often darker than the ones raised in a home tank as the conditions in the wild are often less optimal and food is less available, which results in slow growth and darker snails. The same often applies to snails bought in a pet shop. These snails are often bred in large outside tanks, which cannot compete with the growth conditions of some hobby tanks.
Thin and fragile shell
The growth of the shell takes place in several stages. In the first stage a thin and soft organic layer (periostracum) is deposited by specialised cell near the shell opening (aperture). This is often very well visible in young snails. After the organic outer layer is ready, the snail deposits calcium carbonate crystals at the inside to strengthen the shell structure. It’s at the latter stage (the calcium deposition) that problems can arise if the water quality is not suitable for snails. In practice this means water with a low pH (below 6.5) and low in calcium content. The snails are unable to create a strong shell in such cases and become vulnerable to shell damage, especially when the protecting outer layer has vanished with age (common in older snails of some species). It’s therefore advisable to test the pH if one notice shell problems. For most apple snails a pH of 7 to 8 is optimal. A low pH can be easily corrected by adding calcium carbonate to the water. Most aquarium and pond shops sell special preparation to increase the pH and calcium concentration. Crushed or powdered marble or seashells, lime stone and eggs shells are an alternative for the do-it-yourself hobbyist. Before you raise the pH, make sure that the other inhabitants (fish) of the tanks/pond tolerate a pH of 7-8. Also never increase the pH too much at once (0.5/day max.).
Rough shell surface in new shell parts
The quality of the new shell material depends on several factors: the water quality, the food quality and availability, the temperature, the age of the snail and the general condition of the snail itself. A fast grow does not imply a regular and smooth shell, it can even be the opposite as a fast growing shell can become irregular due to a fast growth of the soft outer layer, while the calcification hasn’t taken place yet, resulting in a maleate surface. In fact, the most beautiful shells are the results of a regular, steady and uninterrupted growth. To achieve this in captivity, one needs to keep the water quality excellent all the year round (regular water changes), and the temperature should stay at room temperature for most of the year, and last but not least: the snails need regularly feeding. The latter factor, the food, does not imply large amount of food, but rather a decent amount at regular intervals. Despite all precautions and care, it can happen that a snail grows an irregular and rough shell. This is often the case in old snails that restart growing due to improved life conditions. There is not much that can be done, except a reduction in food as that slows down the speed of shell growth. Also read this: ‘irregular growth
‘
Regular shell growth (Pomacea canaliculata). |
Malleated shell surface due to fast growth (Pomacea canaliculata). |
Detoriation of shell and operculum
shell detoriation: superficial wormholes; deep holes, loss of shell top
To have a good understanding about the causes of shell detoriation, one needs to know some basic shell anatomy [sread more about shell anatomy here]. The most important thing to remember is that the rigidity of the shell is provided by a strong, calcified inside, with a protective protein layer at the outside. It’s the latter that prevents the chemical detoriation of the calcium at the inside. Once the protective outer layer is damaged, the calcium layer is exposed to the water. This shouldn’t be a big problem, as long as the water is rich in calcium and is not acid, but once the pH of the water drops and the water becomes acid (pH below 7), the calciums starts to dissolve. As long as this process advances at a slow speed, the snails is often able to enforce the calcium layer, although only at the inside. The ouside of the shell is dead material, and cannot be repaired by the snail itself, so once damaged, it will stay that way. The oldest parts of the shell (the shell top) and those places that are often hot when a snail fall on the bottom are also the places that are most vulnerable as the protective outer layer is often damaged at those parts. Problems arise once the shell is detoriated that much that holes are formed, exposing the soft tissues below. In case of large holes, the snail can get problems with keeping the mantle cavity open, with lung collapse and other problems as result. Nevertheless, smaller holes a pose a problem as well, especially in a crowded tank, as other snails and fish won’t hesitate to eat the exposed tissues. Luckily, snails do have some kind of repair system: they simply calcify the exposed tissues to protect them.
 Severely damaged shell (Marisa cornuarietis). |
 Slow progressed shell erosion. Not that the exposed tissues is already calcified. Pomacea diffusa |
So what to do once a snail has gaping holes and or a detoriated shell surface?
First of all, check the water quality: is the pH at 7 or more? (keep it between 7-8). How about the water hardness? (keep the kH and GH high).
A good way to regulate the water quality is to add a source of calcium in the form of crushed egg shells, specialized preparated, crushed sea-shells, marble or something similar. Once you are sure that the water is well enough to halt further deterioration, one has to decide if the shell should be repaired or not. If the snail is active, one can assume that the snail does not suffer from the damage. In such case a repair should be rather considered a protective measurement to prevent other snails from attacking the exposed tissues. If, however, there are no possible tissue eaters like fish and snails around, or if the holes are that small that the tissue stays out or reach, one can choose to leave the situation like it is. The snail will calcify the vulnerable tissues anyway as reaction to the exposition to water.
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 Repaired shell: shell pieces glued over the holes (Pomacea canaliculata). |
If however, a large amount of shell is absent or if there is a real treat for the snail to become eaten alive, once can choose to repair the holes by gluing pieces of snail shell, eggs shells or even pieces of plastic over them. The best glue for this is medical superglue, although common household superglue will do as well, but is toxic until it’s dried. In such case (household glue) one needs to make absolutely sure that the glue does not come in contact with the snail tissues. Pits and deteriorated surfaces can be repaired by covering them with strong nail polish (make sure to use water resistant polish), epoxy resin or even better super glue. The latter dries quickly and even hardens more when in contact with water. More info about shell repair can be found on Pam’s website. She has carried out several experiments with shell repair and has a good practical guide available.
Operculum detoriation: holes, loss of operculum
While the shell mainly consist of calcium, the operculum is build out of proteins, although the species from the genus Pila also have calcium deposits at the body side of the operculum. The operculum is much less vulnerable to detoriations, but if a snail is not well fed, it can occur, however, that the operculum is thin and even get’s holes in it. In such case, there is not much that can be done besides taking good care of the snail. Also keep in mind that the operculum is not essential for an apple snail to survive in a common aquarium with no snail eating fish around. Beside the shape and the smoothness of the operculum, the attachement of the operculum to the back of the foot is a good indication of the well being (or not) of the snail. In normal situations the snail’s tissues completely cover the inside/body side of the operculum. If the snail is not in optimal condition, this tissue is retracted and only the center of the opreculum is covered by snail tissue. In such cases one needs to check the water quality and make sure everything is allright. Old snails can show such tissue retraction as well, while it’s not necessairly a real problem with them. After all, one can compare this with the retraction of gums/tissues around humans teeth if not taken weel care of.Occasionally, it does happen that the whole operculum is lost. This is not a life treatening for the snail itself, but it often indicates a real serious health problem in the snail, so be sure to check the water quality and be sure the snail isn’t dead.
Body and tissue related problems
Snail inactivity
Snail floating
Floating snail. Although often suspected to be a sign of illness, it’s part of the normal behaviour (Pomacea canaliculata). |
If the snail looks like this and floats, you have reason to worry. In this case the snail has died a few days before (Pomacea flagellata). |
Loss of tentacles or small tentacles
The cause of short tentacles or even nearly absent tentacles are often fish. For many fish species, an apple snail tentacle is a fine addition to daily meal and thus they often nip at the tentacles. While sounds and looks akward, the snails often do not seem to suffer very much, at least as long it stays at that level. As apple snails are remarkably well capable to repair their body, they nearly always regrow the lost tentacle, although the new tentacle if often shorter and thinner than the original one. Happily, enough apple snails quickly adapt their behaviour in cases of tentace eating fish and keep their tentacles or the remnants of them under the shell. This is an efficient way for the snails to protect itself, but it takes away much of the viewing pleasure for the snail owner as the snails lose much of their elegance. Therefor it desirable to reduce the number of fish, feed the fish more and if that all does not help: transfer either the snail or the fish to another tank. Besides the aesthetic reasons to prevent the loss of tentacles, animal welfare is also a reasonable argument to avoid this tentacle nipping. One should keep in mind that apple snails in free nature have much more opportunity to hide for fish then they have in a common home aquarium.
Mantle collapse
Collapsed mantle cavity: a lethal condition. |
The mantle is a sac-like structure that envelops the snail’s body and that contains very important organs like the lung and the gills. In normal conditions, the mantle of the snail is aligned with the inside of the shell. Only a thin layer of fluid and slime fills the space between the snail’s body tissue and the shell. When the mantle, however, becomes separated from the shell, it collapses. With the collapse of the mantle cavity, the lung collapses as well. Not only the lung function is severely affected, the gills are also suffering a decrease in function, as the water isn’t able to flow around the gills. While the snail might survive this condition for weeks, it often turns out to be fethal disease. Unluckily it’s not clear what causes the mantle to loosen from the shell and no remedy is known (to the author). If your snail is in this condition, you might choose to kill the snails of the situation does not improve within days. A good way to kill an apple snail is by putting it in the refrigerator. The cold disables the snail quickly and dead will occur within a day. To kill it for sure: put the snail in the freezer after having it in the refrigerator for a day or crush the snails body. Hopefully, you never have to undertake such unpleasant action.
Body disformation
Cancer-like structure on skin (1) and affected siphon (2) (Pomacea canaliculata). |
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Oedema
Old snails sometimes develop oedema (fluid excess in the tissues) and the body of the snail appears to swollen like it’s holding too much water.
Whatever the cause might be, it’s clear that the snail’s fluid balance is disturbed and if the swelling is severe, the mantle cavity is filled with the inflated tissue. In these more severe cases, the lung and gill function is impaired, which of course isn’t beneficial to the snail’s wellbeing.
While some snails die, many stay in relative stable condition. And if they die, it’s not clear what has been the real cause of dead and what was the result of the disease. In other words, an underlining dysfunction could be the real disease, while the oedema is only one of the symptoms, comparable with the oedema in people, where the oedema is often the result of a heart-lung problem. As it’s quite hard to find out what’s wrong with the snail and even if you knew, what to do, there is only one thing that can be done: wait and have patience. You could try to play with the salt concentrations (based on the principles of osmosis) to see if the condition improves, or you can even try to add medicines that influence the water/minerals exchange of membranes, but you should know what you are doing. Keep in mind that animals are living creatures that deserve a respectful treatment and should not be considered as play objects.
Intoxications
Apple snails are very sensitive to certain chemicals and compounds. Unfortunately, some of these chemicals are used to treat fish diseases as fungi and parasites. The basic principle in combating a fish disease is to use chemical compounds that kill the disease, while having no adverse effects on the fish, due to neurological/metabolistic differences between the organisms. However, snails have more in common with many parasites then with fish in the way they react to chemical substances. It’s thus advised to isolate the snails in a separate tank during treatment of the fish unless you are absolutely sure that the product you use doesn’t contain snail-toxic chemicals. And as many disease causing organisms do not survive outside the fish during a few days, together with repeated water changes in the isolation tank, the risk of reinfection through the snail reintroduction can be minimised. Exceptions to this rule are parasites that have a life cycle with snails and fish as intermediate hosts (mainly the case with wild-caught fish/snails). See also here.
A short list with chemicals that are/could be toxic to snails in therapeutic doses:
-Malachite Green (used to treat Ich or white spot, fungi and Velvet or Oodinium).
-Various organophosphorous pesticides like formaldehyde, metriphonate, trichlorphon (= dylox, masoten, metriphonate, neguvon, trichlorophon), dichlorvos and others used to treat infections with flukes, worms, crustaceans and lice.
-metaldehyde used as molluscicide.
-Various copper containing drugs to treat protozoa and fungus infections.
-Parricide D (Di-N-Butyl Tin Oxide) used to eliminate helminthes, acanthocephala, trematodes, cestoda and worms.
A list of fish phamaceutics of several manufacturers with the active ingredients is available on. Many of the preparation listed here could harm your snails!
White patches or spots
A Pomacea flagellata with white spots on the foot and body. These lesions expand at the border and slowly heal somewhat in the center. In case of the authors snails, many affected snails died. |
Parasites
There are several parasites that have snails as an intermediate host. However, apple snails are relatively resistant to many of these parasites, which are often host specific and do not regenerate in other hosts like apple snails. However, at least one parasite (Angiostrongylus cantonensis, a nematode, also known as the rat lungworm), uses the apple snail as an intermediate host. This parasite has the rat as its main host, but humans can be infected when raw snails are consumed. In rare cases this infection can cause eosinophilic meningoencephalitis resulting in severe neurological disorders and even death. But don’t worry if you got your snail from a pet shop, the only way the snail can be infected is by living in water were infected rodents (rats or mice) live. And even then, you have to drink the water or eat the snail or your water-plants (on which the parasites attach themselves after finishing their life cycle in the snails and wait there for being eaten by their main-host). If you suspect your snail from being infected, just keep them away from their main host. This breaks the life cycle of the parasite, and you will get lost of them. Beware that it can take a long time, because many parasites are able to have several generations in their intermediate host. Better thing to do is waiting until the snail has laid their eggs and go on with the young, uninfected snails.
More detailed info on Angiostrongylus cantonensis can be found at:
‘Parasite’ section.
Reproduction problems
Egg deposition
Deposition of the eggs above the waterline (Pomacea canaliculata). |
An apple snail with an egg deposition problem. The eggs collect near the shell opening qnd not on the surface (Pomacea canaliculata). |
Some apple snails are unable to deposit their eggs on the surface they have climbed on. For some, reason, their ovipositor groove does not function adequately or the eggs do not get on the groove. It’s this groove which guides the eggs from opening of the egg-tube (under the shell) towards the top of the foot. In case of an affected snail, the egg mass builds up near the shell opening and stays there. None or only a few eggs are deposited, the others fall into the water, where they drown or become eaten.
Possible reasons (purely assumptions):
1. The snail has a genetic defect that alters the ovipositor groove, rendering it useless.
2. Something went wrong when the snail matured. The ovopositor groove hasn’t come to full development.
3. The snail has grown too large for its species and due to its heavy shell the muscles of the snail cannot keep the shell in contact with the foot all the time. In such case the opening of the egg tube does not make contact with the ovipositor groove and the eggs never get on track.
Infertile eggs
Just like chickens, apple snails do lay eggs even when they are not fertilized. This should be kept in mind of you have a single snails or several snails without a single male. If the eggs never hatch, even not when you are sure that the snails have mated, one should also think of bad conditions for the eggs (dry air, to humid air with condensing water, low temperatures etc.)
References
http://startuptipsdaily.com/snail-farming-in-nigeria/
http://www.agro4africa.com/animal/snail-farming/construction-of-snail-housing/
http://www.petsnails.co.uk/care/feeding.html
http://applesnail.net/content/various/snail_disease.php
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