I have a 5" electric yellow lab he is very healthy and has great color but sometimes his face looks brown or dirty only at certian times. Other times the face is its regular bright yellow. I dont know if this may be a factor but he tends to hide in the rocks alot and seems very shy, and will often hide when someone approches the tank. He is alone does he need a mate to encourage him to come out more? I would like to know what may be wrong with him.