Sick Glowlite Tetra

I agree the the tank does seem a little stuffed. That alone could be causing stress and the discoloration is there are any disputes.

Also, do make sure you have true SAE's not false ones...

No signs of disease though?
 
Yes, they are true SAE's from a very reputable ADA products store in San Francisco. This was confirmed with AC help on an earlier posting, with helpful references having been supplied. And no, I have never seen any agression at all, nor has there ever been any disease in the tank or spots on the fish.
 
While there might not be any visible aggression going on I'm sure some sort of nipping/disputing is going on within the school to cause the fish to lose some of its color. I wouldn't worry as long as it acts and eats normal but definitely keep an eye out.
 
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