Snails in Your Tank- Ugh! or Yay!
When you get new fish or plants, small mollusk hitchhikers may come in unnoticed. What is your first reaction? For many hobbyists, it's "Ugh! Get rid of those things!" I hope this post teaches you to pause and rethink your initial reaction to snails (and other things) we have been taught to be worried about.
What are the Concerns About Snails in Aquariums?
Let's start with some history. I believe the main concern about snails originated from the commercial food fish industry which also translated into the tropical fish trade. Some types of snails can carry parasites that infect some species of fish. These parasites may reduce the growth and success of commercial food fish produced and in high enough numbers can even kill the fish. One example is the ram's horn snail (Bolbophorus confusus) that is eaten by and infects catfish that are then eaten by and live in the intestinal tract of White pelicans. The pelicans release parasite eggs back into the catfish ponds. This is a legitimate concern for food fish and may apply to aquarium if the fish/snails come from geographic locations where the parasite lives and fish/plants/snails are not treated when they are exported before being added to your home aquarium. Having poor living conditions (poor water quality, too small of volume for the fish, stressed fish etc) can contribute to the success of the parasite and increase their effects on the fish in your tanks.
Another concern is that snails will eat fish eggs so fish breeders don't want them in breeding tanks.
Treat Imported Fish and Plants for Parasites
If you are concerned about parasites and keep fish that may be affected (such as large catfish- not Corydoras) and are receiving fish or plants shipped from areas infected with bird parasites (like overseas and the Mississippi River Delta) and you are worried about disease, the fish, plants and snails need to be quarantined for 30 days. Only then can you safely put them in your tank. You may also opt to treat them with heat or chemicals that kill diseases and parasites. Also ask at your pet store or online supplier to see if they treat fish and plants brought in from other countries. Ask what specifically they treat for as well.
Gradually Increase the Bio-load of a Fish Tank
Some aquarists claim that snails have a high bio-load and this is a reason not to have them in your tanks. Bio-load (biological load) is the amount of waste in the water given off by all the living things in the tank. Fish, snails, plants and even feeding all contribute to the bio-load. The amount of bio-load that a closed system like an aquarium can safely support life is determined by the number of good bacteria that can break down the waste and recycle it. If you gradually build up the good bacteria by gradually increasing the number of snails in your tank, then it shouldn't be a problem. Then, when you are ready to add fish, change off some of the water in the tank, remove some snails and add some fish. Then add more fish after a week or so.
I find that the softer-shelled and common smaller snail species (under 3/4 of an inch in size), even in moderate numbers, do not significantly reduce the number of fish that can be maintained in a tank. Nor do they cause you to change the water or filters more frequently. If your tanks have some plants (floating plants or terrestrial rooted plants like Pothos or spider plants) in them, they will absorb the nitrates in the tank's ammonia cycle.
The Benefits of Having Snails in Your Freshwater Tanks
I like having snails and limpets in my tanks! They act as a clean up crew: they eat algae and recycle fish poop into things that plants use as fertilizer and feed baby fish and shrimp of all ages. They are also fun to watch!
Adding Activity to Your Tank
Having snails in your tank adds interest. Snails come in a variety of colors, patterns and shapes. They also vary in behavior. They climb over objects, leave clear trails of eaten algae behind so you can track where they have been. Most snails will congregate at a temporary food source (such as fish pellets) then disperse when the food is eaten. They follow their antennae to a new scent and you can watch their radula (moving tongue) scrape food off the glass. I have bladder snails who will twist and turn when something bothers them. They also move surprisingly fast for a snail! You can measure their growth over a few weeks. They can help pass the time while waiting for fry to be born.
Free Food For Fish
I deliberately grow softer-shelled smaller snails (bladder snails and ram's horn) for my fish. The aquatic jelly eggs and newly hatched snails are great food for guppies and bettas. If I miss a feeding, it's no big deal even in the guppy maternity tank as the parents graze on the eggs and newly hatched snails instead of fry.
These guppies are feeding on the snail egg mass.
Gouramis, loaches, cichlids, puffers, larger catfish, Oscars, goldfish and crustaceans enjoy the more mature snails. Some will suck them out of their shell to eat the meat, others will ingest the whole snail and crush the shell with their stomach muscles. Hard-shelled snails like trumpet and mystery snails work well for large fish who suck them out of the shell or need to wear down their front teeth (like large puffer fish).
Good Source of Calcium
When the fish and crustaceans crunch and consume the snail shells, they provide a source of calcium for them. Crayfish and crabs have exoskeletons that depend on a source of calcium to keep them healthy and molt normally. Don't forget to feed your snails some extra calcium for this reason. Dark green leafy vegetables like kale, spinach, and swiss chard are high in calcium. A cuttle fish bone or even calcium carbonate as a powder can be easy ways to add it to the snail diet. If you find the snail shell breaks easily when you handle them, they need more calcium.
Snails are an Important Part of the Food Chain
They are decomposers who eat poop, and dead and dying things in the tank. Their poop is full of bacteria (as all poop is!) that is eaten by other bacteria. This is eaten by microscopic zooplankton (commonly called infusoria) like euglena, paramecium who in turn are eaten by fish fry and daphnia, rotifers, cyclops, seed shrimp etc. These tiny invertebrates are then eaten by fish who then poop...
While it may appear that some snails eat live plants, (and a few species do!) most are actually cleaning up the dead edges of a damaged plant. They generally prefer dead and dying materials as they are easier to eat and digest. Cell walls in living plants are hard to chew through. When plant cells die, they break open giving the snail access to the inside of the cell.
Clean Up Crew, Tank Five!
Snails are a great clean up crew in a fry tank after the eggs have hatched. They clean up dead and dying fry, the discarded egg case and even fungused eggs. They are a great way to prevent unwanted side effects of overfeeding fry when using flake or pelleted food. Snails can be put into maternity tanks with livebearers but avoid putting them in with unhatched eggs or fry with yolk sacs as they may consume them. Once the fry are free swimming stage, it is safe to add snails. Larger snails like Mystery snails can be great for this as they are easier to move. Snails can be a great addition to shrimp tanks to help clean up.
Bleow these bladder snail function as a clean up crew for my guppy grow up tank and are later fed to larger fish and crayfish.
Snails Are an Early Warning System
If you find that snails are taking over your fish tank and you are not deliberately trying to breed them, they are telling you that you are feeding your fish too much! Snails populations biggest limitation in an aquarium is the amount of food they have access to. The more they have, the more they will reproduce. Large tanks can grow many hundreds of snails before there is much impact on water quality.
During my deliberate high feeding periods, I have hundreds of jelly egg masses in my snail/guppy fry grow out tank. They will keep producing as long as keep feeding them. When I reduce the food, the number of egg masses decrease as well.
So if you notice many snails or many clumps of egg masses, it may be time to look at how much and how often you are feeding your fish before the water gets toxic!
This bladder egg mass will soon hatch!
Create a More Natural Ecosystem
Let's face it! A fish tank tends to be a pretty sterile place to live. Having snails in the tank creates a more natural ecosystem for fish to live. It increases the biodiversity.
Environmental Enrichment for your Critters
Snails are a live food source that doesn't spoil. They also provide a more natural food searching experience for your critter. The process of creating more natural activities for your critters is called "Environmental Enrichment" in the aquarium and zoo world. Searching for food might be the only excitement your fish or crustaceans get.
So, did I pique your interest in snails? Will you not grimace quite so much when you find one in your tank? Might you consider actually culturing them for your fish? I hope you have a little more understanding of their history and role in nature and what they can do for our fish tanks!