Can Mystery Snails Be in the Same Tank as Fiddler Crabs?

Fiddler crabs include more than 100 species of tiny crab in genus Uca. Mystery snails include many genera of family Ampullariidae. Fiddler crabs are brackish water, tidal pool burrowers. They are not fully aquatic and cannot survive in a freshwater fish tank. Mystery snails are freshwater, fully aquatic and tasty to crabs. So, can they share an aquarium? The short answer is "No."

  1. Not Enough Room for the Both of Us

    • You've seen them in a tank in the freshwater fish section. They're so cute, waving at you ... you simply must have one! Don't do it. Fiddler crabs are not fish-tank accessories. They have back-up gills for short forays underwater, but their main breathing apparatus is a lung. They don't live underwater for long -- they even plug the entrance to their burrows and hide out during high tide. Their natural environment is sand banks in tidal regions. They need half land, half water to survive. While mystery snails also breathe air with their lungs, through their siphons, they need to remain under water. It's virtually impossible to have a tank that's large enough to accommodate dual crab quarters, plus snail housemates.

    Dig This Place

    • Don't be fooled by their diminutive size: fiddlers are a keystone species. Their extensive burrowing aerates their natural environment and allows many other species of animal, microorganism and plant to exist on the same sand dunes. They need to burrow, and to do this they need sand substrate. Mystery snails can't tolerate sand, they need smooth gravel to avoid injury and irritation.

    Sucking the Life Out of Me!

    • Fiddlers crabs come from habitats where fresh- and saltwater meet. They can survive in freshwater for short periods of time, but without salt they slowly become waterlogged and die. Water salty enough for fiddlers will quickly suck all the vital fluids out of your mystery snail, leaving a gooey, shriveled corpse.

    A Nice Snack

    • Your fiddler crabs won't mind your snail's untimely end, because they're omnivorous detritovores. They'll happily clean up the remains for you, and they won't mind if you try the whole thing again. You probably won't like this outcome, however, and neither will the snails. Larger and more aggressive fiddlers won't wait for your snail to succumb -- they don't have any qualms about fishing her out of her shell themselves for an early lunch.