SO i started with 6 danios on a monday. By Sunday 3 had died, no idea why (one had a missing eye - might have gotten nipped by a tetra that i returned). The other 3 seemed to be doing OK for the next week, but then on monday morning one seemed to have a wierd lump on his back and today seems really bad. I started api Melafix on monday morning, but today he has what looks like a thick white stripe vertically on his side, and what looks like sore or something on his side. he's not swimming much, just hanging out by the top. I've attached pics. Any thoughts?