Hi, I've had an irridescent shark for over a year now. I also had 4 danios and recently a black molly. My tank size is 10 gallons which is big enough for now because the shark isn't that big yet. My problem is that 2 danios have turned up dead in 3 days. One appeared to have had its stomach eaten while the other was bent. The danios that were killed were the two smallest ones. I have not had a problem with fish being killed until recently so that points the blame at the molly, but it is small. The catfish is a lot bigger than the danios but it is a sissy and not aggressive at all, so I am confused. What do you guys think is happening?