Previously I would have agreed that Ostracods (seed shrimp) are harmless. yesterday, a group of Ostracods attacked, killed, and ate 2 fairy shrimp in my tank.
I personally saw them attacking the first fairy shrimp- it was trying to kick them off. The second fairy shrimp disappeared sometime overnight.
I had previously seen ostracods consume a dead fairy shrimp, but this is the first time i have seen them kill one. I will add some more fairy shrimp to that tank next week and see if I cant get some photos of the swarm.
Here is another creature to add to the harmless list, although I doubt many of you will happen upon them in your tanks.
Clam shrimp - Here are some pics of one I caught wild by dip netting flooded fields. They swim kinda like daphnia by propelling themselves with their antennae. They are much larger than Ostracods. They have a very short lifespan, about 2-3 weeks. The one in these images is about 1/2 inch long.
