Among the infiltrators of your fish tank – parasites, fungi and algae – are snails. With eggs that are often too tiny to see on the stems of plants or carried on fish, they will establish themselves quickly and spread throughout the tank.
The most common of these snails is the pond snail. While it appears to be relatively harmless and can help rid you of algae and other tank detritus, it can also nibble your plants to death. When their population explodes, your tank can look like a snail farm rather than an aquarium.
While aquarium shops sell snail control solutions, this should not be the first step you take to get rid of them. Unless you can pick them out as they fall dead from the chemical treatment, you will end up with rotting snails at the bottom of the tank, which will quickly foul the water.
Three Steps to Eradicate Snails
Your other fish can eat the snails only if the snail's shell is crushed. You can do this by hand if you want, although it can be very tedious and if you're feeding your fish regularly, they'll take the fish flakes before the snails.
The best thing to do is to combine all of the above approaches in order to gain control of the problem. If the snails remain a problem then try a chemical agent. Snails are yet another reason to quarantine plants and fish before placing them into the aquarium.