cool freshwater fish that eats bladder snails.

[sharkweek178]

I second the assassin snail idea. I had a severe infestation of trumpet snails. I introduced three assassin snails, and within about three months the trumpet snails were eradicated. Completely gone. Assassins won't overpopulate either.

By the way, I have couple opinions/experiences that differ from the common wisdom. First, keeping snail numbers manageable is not as simple as "don't overfeed." In my Sumatra biotope, I fed extremely sparingly, and yet the trumpet snails continued to breed out of control. I don't know what they were eating, but it wasn't fish food. (I should note that the tank had a soil substrate, which certainly added nutrients to the system).

Regarding the "don't ever buy a fish to do a job" mentality, I get that too, but I have a slightly different view. To me, an excess in a tank is often a resource that isn't being used, and it's kind of fun introducing a species that will be able to use it (assuming, of course, that there is a species that will do so, and said species will be compatible with my setup, water, and other residents). In my hillstream tank, I am intentionally cultivating algae and biofilm with excess light, for future hillstream loaches to enjoy. When I see snails overbreeding, sure, I'll try reducing feeding. But I'm also thinking, "Wow, some assassin snails would LOVE this!"

In fairness, assassin snails are probably the least bad case of adding an animal to do a job. They're pretty hearty so they can thrive in a variety of conditions and generally the worst thing that can happen is that they won't be as effective as hoped for. And even though my assassins aren't depopulating the pest snails as much as I'd hope, I still enjoy having them.
And I appreciate your view. Because it's not just thinking, 'I'm going to get an animal to do something for me'. You're seeing (or creating) an environment that an animal can thrive in and adding it to that environment. You're thinking of the animal's needs first. But a lot of people don't think that way and the consequences can be pretty bad for the fish and the tank as a whole.

 

[sharkweek178]

@WhistlingBadger
I have to admit that once I curbed the overfeeding, these assassins are really doing a number on the pest snails. After they kill a snail, it leaves behind a shell that turns white. I'm constantly cleaning those up.

 

[WhistlingBadger]

@WhistlingBadger
I have to admit that once I curbed the overfeeding, these assassins are really doing a number on the pest snails. After they kill a snail, it leaves behind a shell that turns white. I'm constantly cleaning those up.

Well, you're smarter than me, then. When assassins started wiping out the trumpet snails in my rice paddy tank, I left the shells in. Soon there were thousands of them, so many that they affected my water hardness and killed off a bunch of my blackwater fish. So, I eradicated the trumpet snails, but they had their revenge.

 

[GaryE]

There are fish that will wallop a snail and then grab the soft bit out of the shell as the animal tumbles through the water column. I had a Betta splendens that did that, and a dozen Bettas that didn't. Some loaches work that way.

Some members of the buffalo head (Streatocranus group) have a long pointy tooth structure. Steatocranus sp "red eye" is amazing with this. They poke a tiny hole in the snail shell, then simply suck the snails out of the shell and pile their empties by the doors to their caves. I would regularly siphon up little pyramids of shells.

If you want them you need a tank with the highest current you can, designed to be the edge of a Congo River rapids.

Some Cichlids have muscular bony jaws that crush snail shells.

But molluscivores are rarely tiny, and rarely any good in communities. It's a lifestyle that doesn't favour living in groups, because of food supply. They tend to be grumpy, territorial loners.

 

[sharkweek178]

Well, you're smarter than me, then. When assassins started wiping out the trumpet snails in my rice paddy tank, I left the shells in. Soon there were thousands of them, so many that they affected my water hardness and killed off a bunch of my blackwater fish. So, I eradicated the trumpet snails, but they had their revenge.

I can't say I was thinking about the effect on water quality. I just didn't like how they looked. But this is good information. Thank you for sharing your unfortunate experience.

 

[GaryE]

I just found some malaysian trumpet snails, after a year without them in my tanks, and I am not pleased. To me, the fact they die while burrowed in the substrate is a constant annoyance. They are terrible for water quality when their population grows.