thanks. Most people think Oscars are all passive, but I must of been lucky to get one that will stand up to most cichlids that are more aggressive. The HITH was getting pretty bad after a while. So I kept the oscar on multivitamins, cichlid pellets, and added aquarium salt. I don't believe carbon would of been the culprit for the making the situation worse, because the disease started to heal up quite nice while using carbon for my canister still. I've noticed after a year, the Oscar has bulked up quite a bit, compared to the first day of having him or her in the 135 gallon.