Well My Cories in My 10 have contracted some sort of Bacteria infection so My Tetras are in the 55 gallon. The severum and other fish never go near them. You will most likely be ok. Try feeding yur sev lotds of veggies. Everyday b4 i go to school i will drop in a piece of lettuce or something. Mine at green beans but left the skin in. Now i just peel about half the skin off and drop it in./