Hi again. Awhile ago I mentioned my common plec had a blistered tail and someone suggested he may be hugging the heater. Well, I went out and purchased a heater cover about 2 weeks ago but if anything the blisters are worse. The tank he's in gets twice weekly water changes of about 20% and the nitrite and ammonia levels remain at nil. Please has anyone any other suggestions. None of the other fish seem affected. 
