Buying fresh fish is simpler than you think. Just keep these guidelines in mind:
A fresh fish should have a nice sheen and springy flesh. A fish should not have a "fishy" odor or cloudy eyes,
Ask your fishmonger where and when the fish was caught, gutted, and cut, and ask for some serving suggestions as well. Remember, practice makes perfect.
Fish School 101: Types of Cuts
Steak: A cut made straight across the backbone through the whole fish.
Fillet: Usually boneless (with the exception of tiny pin bones found in freshwater fish), to fillet a fish, cut along the backbone toward the belly.
Butterflying: To butterfly a fish, remove the tail and spine; open the fish leaving the meat intact and the fish is ready for stuffing.
In the Round: A fish left whole; they are occasionally gutted for retail.