Very nice. No refs? Great imagination. My only thought is that the grasses are a little ...word... sharp. (on their own they're awsome) They tend to draw my eye away. You managed a very real sense of depth and the detail on the fish is excellent.
Cute. I really like the lighting on the fish and through the water.
You might have some luck refering to a couple reference pics though. You could just put fish into a google image search and refer back to a picture or two while your drawing.
Just a suggestion, might help you out along the way.