More then likely the reason is the Nitrate as others have stated....You need WATER CHANGE, WATER CHANGE, WATER CHANGE!!
Just make sure that you are only feeding him what he will/can eat--Nitrates are brought up by to much waist (not only natural waste but also uneaten food) and the best way to get rid of waste is Water Changes.
Just make sure that you are only feeding him what he will/can eat--Nitrates are brought up by to much waist (not only natural waste but also uneaten food) and the best way to get rid of waste is Water Changes.
