Pest Snails

Freshwater snails are one of the most common hitchhikers in aquariums. Whether they arrive on live plants, décor, or substrate, it's only a matter of time before you spot them exploring your tank. While some aquarists consider them pests, most "pest snails" are harmless—and in many cases, even beneficial.

In a healthy tank, snails help break down leftover food and fish waste, contributing to the overall biological filtration process. They also graze on algae and biofilm, helping keep glass and decorations cleaner. Most pest snails won’t damage healthy plants and won’t harm fish.

Personally, I like having snails in my tanks. In moderation, they’re a sign of a thriving, well-balanced ecosystem. But the keyword here is moderation. Given enough food—especially algae or excess fish food—snail populations can explode. And just like any other living creature, more snails mean more waste. Left unchecked, they can begin to overload the system.

Luckily, there are a few easy ways to keep snail numbers under control.

How to Control Snail Populations in a Freshwater Aquarium

Snail Traps

Snails aren’t exactly the brightest animals, which makes trapping them surprisingly easy. If you’re dealing with a snail outbreak, baiting and removing them is one of the simplest and most effective methods.

• Vegetable Bait Trap:

  • Blanch a slice of carrot or zucchini, tie it to a string, and drop it into the tank at night. After a few hours, it’ll be covered in snails. Simply remove the veggie and discard the hitchhikers.

• DIY Soda Bottle Trap:

  • Cut the top off a small plastic bottle (like a 20 oz soda bottle) just where it begins to taper. Flip the top inward, creating a funnel, and secure it in place. Add a bit of blanched vegetable as bait. Snails will crawl in but have a hard time getting back out. Just be cautious—curious fish can sometimes get stuck too.

• Commercial Snail Traps:

  • If DIY isn’t your style, there are affordable snail traps available online or in pet stores. They’re simple to use and can be highly effective.

Chemical Treatments (Use With Caution)

Chemical snail control is effective, but should always be used as a last resort—and only when you’re not keeping other invertebrates like shrimp.

• Fenbendazole (Panacur C):

  • This dog dewormer is one of the few chemicals that can eliminate snails without harming fish. It’s especially useful in planted tanks where removing snails manually isn't practical. However, fenbendazole is not selective—it will kill most invertebrates, including shrimp, ornamental snails, and even some beneficial microscopic life.

Keep in mind: chemical treatments linger in the water unless removed through water changes. Be mindful of long-term effects on your tank’s ecosystem.

A Balanced Approach

If you’ve got snails and they aren’t causing problems, consider keeping them. They can be a helpful part of your tank’s ecosystem—just like algae eaters or scavenger fish. However, if they start overrunning your aquarium, it’s a sign of an imbalance—usually too much food or algae.

Rather than trying to eliminate them entirely, aim to reduce their numbers while addressing the root cause. A snail outbreak is almost always a symptom, not the disease.