i thought it was the fact that people thought they didnt have to do as much water changes since they had carbon, and thus resulted in dirty water and HITH. Never had problems with oscars and carbon before, I thought hole in the head was from stress and water quality (high nitrates).
I am not sure as I havn't kept oscars for too long but I remember a thread about this about a month or 2 ago on here
I am not sure as I havn't kept oscars for too long but I remember a thread about this about a month or 2 ago on here