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Question: Snails are destroying my pond plants. Treatments I've found are not safe for fish and plants. What do I do?
Answer: Sorry to hear that snails are eating your pond plants. While some snails, such as the Japanese Trapdoor Snail, are beneficial to the pond, most snails will devour your pond plants. If snails are eating your plants, then it's a safe bet that you do NOT have the Japanese Trapdoor Snail.
There are a number of ways to try to eliminate the snails. Unfortunately goldfish and koi are not known as snail eaters. More on that later.
Two products that you can use to kill the snails will also be beneficial to your fish at the same time. Both products are designed to kill fish anchor worms. One rather convenient side effect to both is that they just happen to kill snails. YES! One is from Jungle Labs and is called Anchors Away and is a powder. The other product is from Aquarium Pharmaceuticals and is called Dimilin, which is a liquid. You can treat the pond to kill the snails and your fish will benefit in case they have any anchor worms that you have not yet seen. Heck of a deal!
BE VERY CAREFUL and READ ALL OF THE INSTRUCTIONS!!!! Given in proper dosages, both products are, of course, fish and plant safe. Apply only one of these products!
One treatment might not kill all of the snails. Again, READ THE INSTRUCTIONS as to when a second treatment can be given. IMPORTANT: Be sure that you remove all of the dead snails from the pond. If you leave the dead snails in your pond, you will quickly have major water quality problems!!! I can’t stress enough the importance of removing the dead snails from your pond. Live snails are a major source of bad things that can infect your fish. Dead ones are even worse. Just be sure that you've thoroughly examined your pond for dead snails. I would also recommend a major water change.
Another way to control the snails is to trap them. I refer to this method as the "organic snail control" method. This can be done by floating lettuce leaves in the pond. The snails will climb up on the lettuce and you simply pick them off. Of course, this method can also be applied to snails on your pond plants!
As far as fish eating snails, there are some fish that will eat snails. Koi and goldfish are not among the known snail eating fish. I have seen one Internet reference that pond fish will eat snails. But from 15 years of being in the pond business, I have never read/heard any other data that goldfish and koi are a method for snail control. I've talked with lots of people with snail problems, and they all have goldfish and/or koi.
The most exotic pond fish that I know of, sturgeon and sterlets, are carnivores and absolutely love snails. These fish are often described as "prehistoric fish" as they date back to the dinosaurs. In fact, they actually look like something from the dinosaur age. If I had a pond big enough, I would love to have some of these fish. They can be HUGE, ranging in size from 3' up to 20'. (Yes, that's feet!) They are truly an amazing looking fish.
Sturgeons and sterlets will be more than happy to clear out your pond of snails. Frogs too while they're at it. Like I said earlier, unless you have one of the most unusually stocked ponds around, I doubt if your fish will eat the snails. (I personally do not know of any ponds, private or public, that have these fish.)
I believe that a bullfrog will also eat your snails. And your fish. And your birds. And keep you up all night. And your neighbors. Bullfrogs eat just about anything and everything they can catch! You want to stay away from bullfrogs! Bad for your fish!!!!!!
Still another method to control your snails is Mother Nature. Snails burrow down into the muck on the pond bottom to overwinter. Clean out your pond and most likely the snails will die off once cold weather arrives. Well, IF we have cold enough weather!
Whichever method that you use, keep an watchful eye for more snails. Thanks to eggs, chances are excellent that you'll have another infestation that you'll have to deal with. (Snail trivia here: As mentioned earlier, most snails are bad for the pond. One major exception is the Japanese Trapdoor Snail. Most snails lay eggs. Guess which snail is a live bearer, giving birth to little baby snails? The Japanese Trapdoor Snail. Amazing coincidence! Now you can impress your friends with your snail trivia!)
Gene, I hope this helps you get your snails under control. Please feel free to contact me if you have any further questions.
Duane Eaton, Pond Planner (www.thepondplanner.com)