This is the 2nd time i've found a neon tetra missing an eye.
Could it have been attacked? You will fine my tank inhabitants in my signature.
Is this normal though? The eye shouldn't be missing for no reason. I dont see any fins missing or anyhting like that. Just the right eye looks like it popped out. I mean completely popped out. Not like popeye where the eyes just bulge out. The eye is just completely missing and the tetra is laying on the sand just breathing heavily. It still tries to swim around but it can't stay right side up.
Any help on how to prevent this in the future?
29 Gallon tank
~6 Long Finned Black Tetras
~3 Bosemani Rainbows
~10 Serpae Tetras
55 Gallon tank - Planted
~2 Pearl Gouramis
~16 Neon Tetras
~6 Glo Light Tetras
It's more likely, though, that the fish lost the eye to an injury leading to a rapid infection, and the eye just melted. An injured eye might have also made a tempting snack for the other fish, even perhaps the cories.
There's not really a lot you can do about a situation like that. You could try giving the tank a good cleaning to prevent infections, but I don't really think that it would help much.