Last week I wrote a bit about the great health benefits of eating fish and other seafood (click here if you didn't read it). A lot of people, however are intimidated by buying fresh fish. Follow these tips (many of them common sense) and you'll be just fine.
Fish should be displayed on a thick bed of fresh ice or well refrigerated. It should never be sitting in water. The fish should smell fresh, like the sea--not fishy. Ask to smell the fish if you want to. Whole fish should have clear eyes, bright red gills and the flesh should be firm and shiny and should bounce back when pressed lightly (ask the merchant to do this for you). Fillets should be firm, shiny and bounce back like a whole fish. There should be no signs of drying, discoloration or mushiness. Frozen fish fillets are sometimes a good alternative to fresh--especially flounder, sole and some thicker cuts like halibut, snapper, tilapia and salmon. These are OK if you cook them a little more than medium-rare (frozen fillets can be a little stringy otherwise). Tuna and swordfish aren't great frozen unless they're flash frozen on the boat. Never buy frozen fish if the packaging is damaged or there are signs of frost or ice crystals.
Crabs and lobsters are also sold alive--and they should be acting that way. They should have lots of leg movement. Frozen or pasteurized is a good alternative if you don't want to deal with a live animal.
Shrimp, like fish, should be fresh smelling and feel firm. Unless you live near where shrimp are caught, any shrimp in a fish market will have been frozen already. So what you think of as fresh shrimp were thawed already--you just don't know when. So it's actually best to buy frozen shrimp (unless the merchant assures you that they were thawed recently). You want to buy unpeeled shrimp for better taste and texture. The ingredient list on a bag of frozen shrimp should be "shrimp" only--no additives or salt. Wild shrimp are your best bet for taste, although farmed aren't bad. Shrimp are sized by the number of shrimp per pound--16-20, 24-30, etc. The higher the number, the smaller the shrimp.
Frozen is your best bet for squid and octopus as well, but if you can get fresh, use the fish rules (fresh smelling, clear eyes, etc).
Fish stored at 32 degrees lasts twice as long as fish stored at 40 (the typical fridge temperature). When you store fresh fish, put it in a zip-top bag and keep it on ice (or cover with freezer packs) in the back of your fridge and use it within 2-3 days. If you go beyond that, wrap it tightly in foil and plastic and freeze until you're ready to use it.
Ideally, frozen fish should be thawed in the fridge overnight. Remove it from the package, put it on a rimmed plate (to catch any water) and cover it with plastic. If you need to thaw it faster, thaw it in cold running water in the original package.
I hope this gives you a little bit of insight of what to look for when shopping for fresh seafood. Check back later in the week for some easy recipes that you can make with your newly bought seafood.