Hi everyone I have the arowana was alway keep laying on the bottom of the tank, when he swim his head getting down and the tail going up . He just start doing for last 2 day , before that I haven't do anything about the water, but I have change 80% of the water in 2 or 3 week ago. I only feed him bloodworm and mealworm and shirmp . Does anyone how to treat it ? Please help me

