Hi! I just joined this website and was hoping for some advice. I have two black ghost knife fish in a 55 gallon (US) tank that up until recently (last 72 hrs) were tank mates with a rainbow shark, 5 tiger barbs, 2 plecto catfish somethings and two sucker fish ... all of these died within in 48 hrs (over the last weekend)and the ghost knife were the only survivors. I had them all for approx 6 months. I had never seen any problems between the fish apart from a little chasing etc. The tiger barbs hung out in the same area as one of the BGKF, but it seems this could be rare? I want to get some other fish but need some advice on what would be the best. Thanks for any help!