My opinion,
1. Its just not a wow photo .. grunts in wide angle arent a wow fish, and arent normally in a wow situation.
2. This particualr shot would be more interesting if shot more upwards to create a gradient blue
3. Post processing seems to have gone a bit too far, show us the original, as this one does have fake looking colours and contrasts.
4. Diffuser always helps with reflective fish, as does not shooting flat at them (i.e. shoot upwards and you can expose easier with a flash as the bounce doesnt come back at yo so much)
5. It seems too busy, a little messy i.e. the fish were just there, if you wait with grunt they do polarise into formation which always looks more organised and hence less confusing to look at. for example .. in this photo i find myself trying to pick out a subject fish, where as if they are all facing the same direction the entire school is the focus or subject.
basically very similar to what everyone else says.
Giles