Aquatic snails are often regarded as pests and many hobbyists go to significant lengths to prevent snails entering their aquarium. However, this reputation is misplaced, as most aquatic snails do no harm to the aquarium or the inhabitants. On the contrary, aquatic snails aid in the removal of algae and are a natural part of aquatic ecosystems.
There are several types of aquatic snail that are commonly found in aquariums, these include; rams-horn snails, tadpole snails and trumpet snails. Ramshorn snails (Planorbis spp.) have flat, spiral shells and most are less than a half a centimetre across. Tadpole snails or pond snails (Physa and Physella spp.) have bulbous, translucent-brown shells up to a centimetre long. Trumpet snails or Malayan live bearing snails (Melanoides tuberculata) have conical shells up to a 2.5cm long.
The Good, The Bad and The Ugly
Aquatic snails have positive as well as negative qualities. Malaysian Trumpet Snails do an excellent job of keeping the sediment clean, consuming organic material and preventing excessive anaerobic decay. These snails are often introduced to ‘dirted tanks’ for this reason. Their burrowing activities aerate the soil and prevent toxic compounds, such as hydrogen sulphide from forming. Ramshorn snails are proficient algae eaters and are able to consume algae growing on plant leaves more thoroughly and delicately than algae-eating fish.
Aquatic snails are a good indicator of the health of an aquarium. Their populations will go up or down depending on how much they have to eat. A high density of snails indicates that you may be overfeeding the fish. Most snails eat fish faeces, uneaten fish food, algae and decaying plant material. Aquariums which contain high levels of these elements will likely display other signs of an unhealthy system, including; overstocking, overfeeding, under-filtering, insufficient water changes, minimal aquarium cleaning, and poor plant growth. Therefore, large snail populations are a symptom of underlying problems rather than a problem themselves.
Aquatic snails can also be indicators of sudden changes in water chemistry or quality. Turret snails in particular will leave the substrate if they feel stressed and move to the top of the aquarium where the water is most richly oxygenated. If hundreds of turret snails suddenly appear at the waterline, it’s a very good sign there’s a serious problem with the aquarium.
On the other hand, excessive numbers of aquatic snails are unsightly and add appreciably to the stocking level of the aquarium. Should the aquatic snails die all at once, the subsequent processes of decay will add ammonia to the aquarium water. However, this is seldom a problem.
There is no need to be concerned about the presence of snails in your aquarium. Getting rid of snails requires more effort than it is worth. It would be more sensible to address the underlying problem in your aquarium. If the snail population is low then there is no need to worry, however, if there are hundreds of snails in your aquarium then there is an underlying issue, such as overfeeding and minimal maintenance. Address those issues and you solve your snail problem.