Watch those nerite snails


Olive nerite snail (Neritina reclivata) on tank glass. Photo by author.

For those of you looking to add a glass/decoration cleaner to your tank, consider the nerite snail. I’ve posted before about using nerite snails to clean up diatomaceous algae aka brown algae. They are great cleaners, inexpensive, available, and require little maintenance. 

I want to focus on the word “little” from the previous sentence.  Yes it is true that you don’t need to feed these snails provided you have a constant supply of brown algae. They will eat other algae types, but they LOVE brown algae. I mentioned in that previous post that, if you have multiple nerites, you will likely end up with egg capsules on your glass and/or decorations. Removing those capsules isn’t what I’m referring to either when I say “little maintenance,” (hint: those capsules will eventually fall off on their own). And don’t worry about the snails reproducing. Though they can reproduce in fresh water, it’s not common and the egg capsules are typically infertile.

What I’m referring to with the word “little” is that nerites aren’t maintenance free. They do have some minimal requirements, which you can look up yourself (or see my post about them where I have a couple of links). Though they require little effort on your part, you do need to be mindful of them. If they get turned upside down, sometimes they can’t right themselves. What happens when they can’t? They die. This doesn’t happen immediately if they get turned over, but will eventually. I mention this because you will inevitably discover some of your snails upside down. How does that happen? I can’t say for sure because I’ve never witnessed it but I have a few theories. 

One is that they get knocked over or knocked off the glass/decorations by the fish, either accidentally or intentionally. I have never witnessed any of my cichlids bother my snails, but that doesn’t mean they haven’t. I’m guessing I probably have close to 20 snails spread out among my tanks. Every few days or so I will spot a snail upside down on the substrate. I don’t know how it got there but I know it needs to be turned upright. 

Second, I think they sometimes just “lose their grip.” If they’re transitioning from one rock to another or they try to go from one plant leaf to another, they may fall off. Like I said, I haven’t witnessed this, but it certainly seems plausible. 

Third is that they just simply die. Usually, when I find a snail upside down it is alive and just waiting to be turned back over. However, sometimes they do die and they’re upside down when I find them. Not sure if being upside down is what killed them or they died and the shell got overturned by a fish that swims by quickly, the current, etc. They are very light and, if not alive and attached, the shell can just roll over at the slightest movement. Leaving a dead snail in the tank will contribute to fouled water, just like a dead fish. 

I do a snail “head count” when I feed my fish. Depending on how much cover is in the tank, the snails are usually easy to spot. They’ll be where there is algae and algae requires light, so it’s unlikely you’ll find them under rocks and places where algae doesn’t grow. In the past week, I’ve discovered upside down nerites in two separate tanks. I righted them both and, within minutes, they were both off in search of their next meal. So if you choose to add nerites to your tank, keep an eye on them. 

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