hmm, not good, so it wasn't faeces then? He is still alive but not looking too great, could it have spread to my other fish?
Should I remove him?
Extra info: I added a few rummynose 2 weeks ago & they showed signs of neon tetra disease so I had to get rid of them, after I added them 1 danio start doing nosedive somersaults into the gravel, it went on for 2 days before I had to put him out of his misery. That was over a week ago & I cleaned everything in the tank in boiling water.
What do I do here? I'm a newb so any advice appreciated.