Snails in the Aquarium. Friends or Foes?
Written by Friday, 22 February 2002 00:00
One of the most common problems encounter in aquariums is the presence of snails. Usually the come out all of a sudden and then occupy the tank. Some think that their presence is an advantage since they are great scavengers and will eat all remaining food while some of them will even eat algae. Moreover, they are a part of the natural environment On the contrary, some hobbyists think that they have nothing to offer while they increase the bioload of the tank, and ruin the appearance of their display tanks. Of course, both approaches are justified. No matter which view we take it is true that when their number exceeds some limits some measures have to be taken. Since these snails are known egg eaters, they can’t be left uncontrolled in tanks housing fish which use to lay their eggs. I remember that my Kribensis whenever they had eggs in their nest, they always tried to keep the snails away from it.
There are many species of snails which can live in a tank. Some of them don’t come free like Ampullaria sp. These snails will grow to a large size (equaling that of terrestrial snails). It is a very good scavenger, feeding on the food remainders but when this is not enough it will also feed on the plants of our tank. It will lay its eggs out of the water (usually on the tank cover) and the small snails just drop in the water after a couple of weeks. They can be fed directly with flakes. It has a respiratory organ resembling the elephant trunk which it uses to breath air when the water quality is not very good. When not in use this organ is hidden. If threatened it will hide in its shell and cover itself with a protective cover. This snail is not difficult to be kept under control mainly because of its sheer size.
Other snail species which may find their way in our tanks by accident (usually with the plants we buy) are the following:
1. Helisoma nigricans which is a species native in Brazil. It has an almost circular shape and its diameter may reach 1.8 cm. Its color is red and is very sensitive at temperatures below 20oC when it usually dies. It is a vegetarian and usually lives on plant leaves which also become its favourite food. A solution is the addition of fresh lettuce leaves in our tanks – which will only partly solve the problem. A close related species which is found in Central Europe is Planorbis corneus. It is absolutely harmless but is very demanding as far as water parameters are concerned – it will not survive at a pH higher than 7.0.
2. Melanoides tuberculata (also known by the common name Malaysian trumpet snail) is perhaps the most common snail found in our tanks. It is found from Egypt to India and it needs a water temperature of at least 20oC. It can’t live in soft water because it needs the salt to build its shell. It is a livebearer snail which is fed exclusively on algae and food remainders which make it an excellent scavenger for any tank. It is a nocturnal snail, staying all day under the gravel and gets our only after the lights of the aquarium have gone off. This habit doesn’t allow us to know the size of the snail population unless we suddenly turn on the lights, 2-3 hours after. Then you can see them all standing on rocks, stones and on the glass. After some time they will increase in numbers and soon you will have the impression that your gravel is alive because it moves (due to the moves of the buried snails). This also helps the plants because it increases the aeration of their roots. I have never encountered any problem with this kind of snails and I have too many in my tanks. The only “disadvantage” is the fact that they get everywhere, including the filter cartridges, the intakes, even the pipes. This calls for a more often service of the filters because their flow capacity is greatly reduced. Sometimes, you can see tens of small snails on the surface of the water, which is usually a sign of poor water chemistry. The sight of adult snails out of the gravel during the daylight, is also a sign of poor water chemistry.
3. Lymnaea stagnalis is a particularly harmful snail which only feeds on aquarium plants. If it makes its way in your tank it is quite hard to eliminate it. Usually it is introduced with live food or newly purchased plants.
Some of the snails mentioned in this article are useful for our tanks and will nor pose any problem to the hobbyist. This is true as long as their population size is under control. Wrong feeding is the number one reason for them filling our tanks. When food is left over, they will happily get it and this will result in a huge snail population very shortly. If we ever come across this problem, we must find a way to get rid of them.
Reducing the snail population
The best proposal is to add some fish that feed on snails. The best candidates to do the job are the various species of the Botia genus and the species Tetraodon fahaka strigosus (a freshwater puffer).
Botia macracanthus (common name: Clown botia) are the best known species of this genus but they have needs which must be taken into account. Thus, their final adult size exceeds 20 cm and we must keep a school of 5-6 specimens for them to feel “at home”. These fishes can live 20-30 years and they need a big tank to thrive. The same is true for Botia modesta (common name : blue botia; final adult size 24 cm) with the advantage that you can keep less specimens (2 per tank). However, even an 150 x 50 cm tank is small for these fishes. In a smaller tank (100 liters) 1-2 fishes will live 4-6 years and will never reach their final size. An alternative solution is the smaller species of this genus like Botia dario (maximum size 7 cm), Botia lohachata (maximum adult size 7 cm) or Botia striata (maximum adult size 10 cm). For smaller tanks, Botia sidthimunki is proposed (maximum adult size 6 cm). Botia morleti (another small Botia sp. very similar in shape and color to Botia modesta) is not recommended for community tanks since it has the nasty habit of nipping on other fishes’ fins.
Tetraodon fahaka strigosus is regarded as the ideal fish to eradicate the snails from any tank. However, there are some drawbacks here, too. Firstly, this is a brackish fish and it will only survive in such water. Secondly, it is a fairly aggressive species and will not hesitate to ear fry of other fish if available. Their behaviour in the tank will definitely cause stress to other fish and – very often – casualties. In short, one must think very carefully if this is the right addition to his tank.
It has been suggested that Anomalochromis thomasi, a west African cichlid is a good candidate to eradicate snails. This rather peaceful cichlid will only grow to 10 cm and have a characteristic colouration. They can be easily added in a community tank.
Finally, species of the genus Synodontis are also regarded as efficient snail eaters.
Is there really a reason to get rid of the snails in our tank? More often then not, the answer is “no”. Melanoides tuberculata in particular do an excellent job in the gravel and recycle a lot of uneaten food. If sand is your substrate, those snails will not be able to bury in it and will choose shaded places to spend their day.
If we assume that despite the correct feeding habits and the introductions of suitable snail eating species their population is still out of control, then you can use a specially designed trap from time to time to collect them. You can also make your own trap with some uneaten food in it, which will be dropped in the water when the lights go off and collected some hours later – it will be full of snails.
What I regard as an unacceptable solution is the use of the special medications which are commercially available. Even if we assume they are safe for your fish and plants, still killing a large snail population in one shot, will create a much more serious problem than the one you are trying to treat.
Published by permission.
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