What's wrong with my Barb's eye?

helpcomputer

This morning when I woke up and checked on the tank everything was normal. Had to go to my brother house in jersey to help him paint, came back an hour or so ago and noticed one of my barbs' eyes has a weird looking grey half-ring around the top of his eye.. is this just a battle scar, or an infection? It doesn't seem to be slowing him down at all, his other eye and his companions' eyes look fine.

Lupin

What are the water parameters right now?

Cody

Also, what is the tank size and tankmates?

helpcomputer

tank 40g, penguin 350 filter, albino chocolate pleco (2"), managuense (2.5") green terror (3"), and 3 barbs. negative on the test kit.

http://img98.imageshack.us/img98/4728/picture006ut1.jpg

terrible pic, sorry. best i could do, jittery bastich.

helpcomputer

He's uh, fine now? This morning you wouldn't have even noticed something was wrong with him...

helpcomputer

Nevermind.. turns out it's only visible (to me, anyway) at night. What could be wrong with him?