I think i fed the older lot too early. they were swimming around but kept falling back to the ground and lying there. i fed them and yesterday morning they were all dead so no black ones for now.
the zebras are all alive still though, and im going to wait until they are actually swimming before feeding this lot :-?
a definition of free swimming would be good. is it when they detach themselves from the pipe, or when they swim a bit and then sit on the ground again, or when they swim constantly?