Red Tail Black Shark Illness?

[pwilson66961]

I'm new to this forum but was wondering if anyone could help? My red tail black shark which I've had for about 3 years has started to get a white ring around his left eye. It appears to go all the way around and was wondering if this is an disease / illness or if it is something normal that happens with this species of fish. Any help would be much appreciated

 

[big_sw2000]

Cant really help you hear, but my shark is about 3 years old. Close to 5 inches, and he has no white ring. Its not something ive heard off before.

Steve