Pest Control

For this post I thought I would talk about one of the most common, albeit more trivial problems that almost all aquarists will have to deal with from time to time – snails.

Generally speaking, snails in an aquarium pose little threat other than being unattractive. Although they may eat some more sensitive plant species, the majority of plants will be left untouched as the snails prefer to eat fish food, algae and rotting plant material or dead fish.

Snails usually enter a tank as eggs hitchhiking in on live plants, and once they are in the tank it is unlikely you will ever be truly rid of them. That being said, there are several advantages to having a population of snails in an aquarium; they help to clear up decaying organic matter preventing it from affecting water quality and they can help aerate the substrate, however if the population gets out of hand – which can happen very quickly especially with the hermaphroditic ramshorn snails – you may wish to consider some methods of pest control. There are several ways to limit snail populations, as outlined below:

  • Chemical additives: my least favourite but probably the most effective method to get rid of pest snails is to buy commercial snail poisons. Whilst these chemicals are generally harmless to fish, certain sensitive species may suffer following the addition of some snail killing chemicals. These are also a definite no-go if you have shrimps or other invertebrates in your aquarium as these will also certainly die as a result. The other issue with this method is that it won’t prevent the population re-establishing should a couple of individuals survive, or fresh eggs make their way back in.
  • Monitor feeding: one of the most common causes of an explosion in snail population is over feeding. If the fish aren’t eating all the food within a few minutes and it’s being left sitting on the substrate, the plentiful supply of highly nutritious food will fuel an exposure in population – reduce your feeding and you should  slowly see a reduction in numbers. This is probably best used in conjunction with one of the following methods below.
  • Physical removal: one of the most effective methods for reducing the snail population is to physically remove individuals. This can be done by hand but more efficient methods include using the syphon during a water change – smaller snails will get sucked out of the substrate and will collect in your bucket – make sure they don’t go back in with the clean water. Commercial snail traps can be purchased that trap the snails using fish food for bait, the trap can then be removed and the snails destroyed. One of the easiest methods is to place a piece of vegetable (blanched lettuce or courgette etc works well) on the substrate over night, and in the morning removing it with the snails attached.
  • Destroy eggs: One very effective method of keeping the numbers down is to destroy any eggs you see. these usually appear stuck to rocks, wood or leaves and look like a small transparent slug full of little white dots. They can easily be scraped off the surface and detroyed, or to be extra thorough with rocks or woodwork I sometimes remove them entirely and soak them in boiling water. Combine this with pysically removing the adults and the numbers should soon plummet.
  • Stack the food chain against the snails: the main reason snails can get out of control in aquaria is because they have a plentiful food supply and no predators. If your tank is home to the ususal community fish the chances are very few to zero snails are being eaten. Buying certain species of fish can help re-dress the balance and create a more sustainable ecosystem. I must stress here that buying fish purely to eat snails is not a miracle cure and you should always make sure any new fish are compatible with your existing set up. A few commonly seen snail eater include:
    • Loaches: most members of the loach family are well known as snail eaters however some get quite large so should be researched thoroughly. A smaller one I keep in my smaller aquarium to help keep snails in check is the zebra loach. You will soon start to notice during your water changes that you are sucking up a lot of empty shells instead of live snails – the proof of your loaches’ hard work! It should be noted however that it is unlikely that loaches will completely rid your tank of snails as they will also eat the normal fish food added for their tank mates, however they can certainly be useful for keeping the numbers down.
    • Puffer fish: most puffer fish are voracious snail eaters, I can personally vouch for the Indian pygmy puffer, my tank is now littered with hundreds of empty snail shells, however this is where the good news ends. In my opinion no puffer can be truly considered a community fish and most require fairly specialist set ups. I use my puffer fish as snail disposal rather than snail control – rather than just tip all the snails down the drain with the water I give them to my puffer and there is now essentially a free food supply as the snails in the puffer tank breed quicker than they are eaten! Generally however not one I’d recommend to control snails in a community tank.
  • Snail eating snails: possibly my favourite method and one I have employed in two of my tanks is the assassin snail – a more attractive snail than the pest snails and a much slower breeder (the assassins require a male and female to breed, whereas ramshorn snails are hermaphroditic). The assassin snails will hunt the pest snails, or wait in the substrate for a prey snail to come within range before eating it. Among the benefits of keeping assassin snails is that they wont overrun your tank, they are harmless to other fish and plants and they are a natural choice that doesn’t impact water quality. They are also a sustainable choice as provided you bought enough individuals to start with they will breed and maintain or even increase their numbers. They may never rid your tank entirely but hopefully will keep numbers of pest snails down. Should the numbers of pest snails get very low then the assassins will happily graze on uneaten fish food, ready to pounce should pest snails proliferate again.

So there we have it, some of the best ways to counter a pest snail invasion – hopefully someone may find it useful!

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