Water Fleas??

[Steph_D]

I have a 5 gallon tank that I'm using as a snail tank and I just noticed something moving around in there a LOT faster than I've seen any snail move. They're about the size of the eyes on this smiley , white, and they move pretty fast. I was thinking that maybe they're water fleas? There's no way on earth that I can get a picture. Would they harm my snails? If I put a fish in there, would they eat them?

 

[Lotus]

No, they won't harm the snails. Fish will most likely eat them. A lot of the small "critters" that turn up in a tank multiply when there is excess food around, so feeding a little more lightly or more frequent water changes/gravel vacuuming should solve the problem.

 

[Etheostoma]

Sound like what you've labeled them, cladocerans, "water fleas". Fish food. Non-parasitic. Only thing they eat is suspended algae, bacteria, or food particles that are too small to see.

Daphnia longispida and Daphnia magna are both probably too robust for a fish under 3-inches to swallow. Especially small-gaped aquarium species like tetras, danios, gouramies, and smaller barbs. Commercial algicides containing (get ready) poly(oxyethylene(dimethyliminio)ethylene(dimethyliminio)ethylene dichloride)
will flat kill them dead at the recommended doseage.