Whether you want them or not, the odds are at some point that snails are going to show up in your aquarium. And usually it won’t just be one or two small snails. In most cases, they’ll appear like an Old Testament, Biblical plague, and cover your aquarium in a blanket of plant munching gastropods.
The good news is that not all snails are created equal. Several species of the more commonly found aquarium snails are actually beneficial to an aquarium – as long as you can live with the somewhat unsightly masses of them clinging to your ornaments and glass.
On the other end of the spectrum are the major pest snails – the ones that will devour a carefully planted aquarium like a plague of locusts. These are the snails that can ruin a carefully aquascaped aquarium in a matter of weeks.
Below is a list of the more commonly found aquarium snails, which will help you identify any hitchhikers that make their way into your tank.
Pond Snail – You would be hard pressed to find anyone who actually wants pond snails in their aquarium (unless they are breeding them for Dwarf Puffers or other similar fish). While they may serve some purpose in outdoor ponds, they are considered one of the worst pests in home aquariums.
Pond snails are hermaphrodites, and in small numbers, are capable of self fertilization. So if even one pond snail manages to make its way into your aquarium, you will soon be dealing with hundreds – if not thousands of these snails.
And if dealing with hordes of these snails isn’t bad enough, they love to eat plants. So once their numbers reach critical mass, they will will start to eat every plant in sight.
The term “pond snail” actually refers to several different species, and their sizes can vary greatly. Greater pond snails can grow up to 2.5 inches (7 cm), and have an elongated spire, while lesser pond snails can be as small as 0.11 inches (3 mm). Regardless of the species, they are all pests and should be removed as soon as possible.
Ramshorn Snail – Ramshorn snails are considered a moderate pest, though there are many people who appreciate the look of their colorful shells.
Like pond snails, they are hermaphrodites and breed prolifically. Once introduced to an aquarium, they are nearly impossible to eradicate. However, they rarely eat plants, and seem to focus more on algae and leftover fish food. Their numbers can be controlled by ensuring that you don’t over feed your fish.
The name ramshorn snail actually encompasses numerous species, and they may range in size from a 0.11 inches (3 mm), to 1.25 inches (3 cm). The colors also vary wildly, and you may find some with nearly translucent shells, while others have almost completely black shells. Brown and red shells seem to be the most commonly found colors though.
Malaysian Trumpet Snail – The Malaysian trumpet snails are a boon to some, and a pest to others. Many aquarists (myself included) swear by this snail, and include it in nearly all of their aquariums.
The reasons that many people actively culture this snail in their aquariums are simple – they devour algae, and perhaps more importantly, they aerate the substrate. This is very important if you use a substrate like sand, since deadly anaerobic pockets can build up if the substrate isn’t regularly aerated.
But it’s also easy to see why many people consider this snail to be pest. They almost seem to be born pregnant, and due to the fact that they burrow and hide in the substrate, it is almost impossible to ever remove this snail from an aquarium once it has become established.
Assassin Snails – These are a relative newcomer to the aquarium scene, and like the name implies they prey on other snails. While many people would be more than happy to have this hitchhiker in their fish tank, it can wreak havoc on established snail populations.
Thankfully this snail reproduces sexually, so there needs to be both a male and a female in the tank. Also, they reproduce relatively slowly, so if they are caught early enough, you can usually remove them from the tank.
However, they are capable of burrowing into the substrate, so even if you think that the problem is under control, there may still be a number of them hiding and reproducing in the aquarium.