sick shark

tank details: I have a 65 gallon tank. Ph 7.0, ammonia and nitrates 0. 2 balla sharks (4-5in long) (1 year old) 2 rainbow sharks (2 years, 8 months) 2 cherry barbs (4 months) 2 angel fish (1 year old) 1 panda cory (2 years) 1 pleco (2 years) filter- 110gal with biome and carbon Tank was...