Whats wrong

[Dearra]

Could somebody please help me. Last night, I noticed one of my Discus was very dark (nearly black) and looked sort of skinny and hiding in a corner.
This morning it took me about 10 minutes to find where he was, and he looked the same. Checked my water for ph, ammonia, nitrite, and nitrate. There was nothing wrong with the water. About 30 minutes later when I was going to do a water change he was back to his normal colour and swimming around. He has been fine all day, except when I fed them today I took notice of what he was doing. I gave them all some colour bits, and he couldn't seem to get any in his mouth. So I put some crumble in for him which is smaller, and he couldn't get that in his mouth either. All the others don't have a problem. I have had him for about 5 months and never really noticed before if he has been getting any food. Maybe he is only eating the frozen food, because he wouldn't still be alive otherwise. Anybody got any ideas on what could be wrong with him. He has been quite a healthy looking fish since I have had him.

Thanks
Dearra

[Nathan]

fist things you should post your water parameters, ph ammonia temp etc. this way we can get a better idea on if there is anything wrong with the water.

i notice that my snakeskin also gets quite dark now an then, i find that he gets dark when he is 'sleeping' so this maybe possible, also sounds a bit funny depending on the weather, ive noticed he gets darker when its raining.

has there been any fish beating up on him or anything that youve changed that could possibly be stressing him out?