The nassarius snail, N. vibex, is a small member of the mollusk phylum and is a fairly common addition to the saltwater aquarium as part of the clean up crew. They are amusing to watch. By day, they bury themselves in the sand, with just a tiny periscope-like piece of flesh left sticking out of the tank.
When you feed your fish, you’ll think you rang a dinner bell, because these snails will come crawling out from the sand bed like zombies from the night of the living dead.
But are they really an essential part of the reef cleanup crew? That appears to be where the controversy about the nassarius snail resides.
If you plan to keep them in your tank, you should have a deep sand bed. These critters aren’t really appropriate for a bare bottom reef tank.
Nassarius snails (or pretty much any snail, for that matter), are not compatible with hermit crabs or shrimps, which will prey on and turn them into escargot. The hermits may even turn them into a mobile home.
What do they eat?
If you’re like me, I think of snails as being useful to keep the problem algae population of my tank down. But that’s not the case with the nassarius snail. These snails don’t eat algae they eat carrion, which is a fancy word for dead fish. That’s right, not only does the nassarius snail crawl out of the substrate like a zombie, but it also has a craving for flesh, not algae.
Are they poisonous?
No, these sand-burrowing invertebrates are not known to be poisonous.
Will they eat diatoms?
No, these are carnivorous mollusks that prefer to eat dead carcasses (kind of like tiny, underwater vultures…with shells…ok that was a stretch).
Do they need sand?
Nassarius snails burrow into a substrate, when they are not active, so you should have some sort of soft substrate like sand or mud.
Do they breed in captivity?
Aquarium owners report and post that a happy group of snails have laid eggs in their tanks (on the aquarium glass, for example), but this is a very difficult species to raise in captivity. The most likely result is that they’ve created a natural zooplankton bloom in your tank, feeding some of the other invertebrates (or fish).
So, are nassarius snails useful?
Well, if algae are your problem, keep on shopping, the nassarius snail won’t help you there. If dead fish carcasses are your problem…well…the nassarius snail will help you there, but you might want to follow the process upstream a bit and figure out while you have all those dead fish carcasses in your tank. No seriously. That’s weird. What’s going on?
In all seriousness, the nassarius snail can be a bit helpful. The fact that these cleanup critters zoom out from the sand bed at the first sign of feeding your tank is a signal to me that they will and do eat excess (I assume meaty) foods, but there are also reports that the nassarius snail will be a predator of the other tiny invertebrates in your sand bed that you were helping to grow. But the challenge with keeping them in your tank is that they may help clean up excess meaty foods, but if you don’t have a lot of excess food (probably a good thing) they may starve.
Are they part of my cleanup crew?
In the past, I have added them to my tank, but I do not have these snails I’m my tank currently.
For more information
- Shimmer, Ronald. Marine Snails. CORAL magazine. July/August 2015.
- Best herbivores. Worst herbivores. CORAL magazine. July/August 2015.
Check out these carrion eaters in action:
I would characterize the nassarius snail as:
- peaceful and easy to add to any tank with a sandy substrate
- interesting to watch
- possibly helpful
- certainly not an algae eater
For further exploration, I would be interested to see if adding these carrion-eating snails helps to keep bristle worm populations in check, but competing for the same food. I don’t have research to support that, I’m just hypothesizing. So if you absolutely hate bristle worms, that may be another reason to try them.
If you were interested in this snail because you thought it would help you with problem algae, I encourage you to check out trochus, turbo or astrea snails, instead.