need your help

Question
i need your help sir.I have a 3.5 inch flowerhorn.He doesnt swim around instead he stays on a portion of the tank without moving.the inside of his gills were pink but now it is dark red in colour .Is he bleeding?if so how should i treat him the outside of his gills have become somewhat blakish as though he has burnt himself,please please help me .there is no chlorine in the tank

Answer
Hi,
The darker color red is actually a good thing. It means that it is getting the maximum amount of oxygen and nutrients to the fishes blood. As for the black, Is there any chance you can send me a picture? It's not essential, but it would be helpful. In the mean time, don't worry too much about it.

It is perfectly normal for cichlids to create a territory and stay in it, and not move out of it. Is he digging a whole in the gravel?