They are the little fleas of aquaria and a treat for my bettas.
Home is my Shrimp tank with Ramshorns, pond snails, PFR, PRL,& Red Rilis.
They actually feed on whatever the snails dont deal with. From my experience they are too fast for most fish except the real hunters like SAE or if the random cory stumbles on a pair coppulating. Otherwise, they dont bother anyone nor the plants in the tank. This tank actually has some good mojo because my mosses oddly grow the fastest in this tank. If you want some, lmk. i have about 30 in a container ready to go.