I have a silver arowana (draco) he is about a foot and a half long, and my sting ray (fishsticks) who are in a 220 gallon tank. Draco appears to have fin rot, its continually getting worse. I feed both of them in the morning and at night, sr gets blood worms, black worms crawlers. arowana gets crawlers, pellets, krill. there is never any food left in the tank after feeding. I change about 20% of the water twice a week for a total of 40% a weekly. The water test strips say every thing as far as water goes is A OK. Im hoping some one will have a medication sugestion that will allow me to treat the tank with both fish in it. also one as to why this is happening? 
Thank you!
Thank you!
