Not everyone can go out and catch their own fish to guarantee freshness. So, How do you know a fresh fish when you see one?
Here's how to know what to look for...
The fish's eyes should be clear and bulge slightly - Cloudy sunken or indented eyes means the fish isn't at it's freshest.
Whole fish or filleted fish should have firm and shiny flesh. If you can rely on your sense of touch (by that I mean if the fish monger will let you or if it is packaged) press the skin, if it remains indented and doesn't spring back up this is another sure sign that the fish isn't at it's freshest.
Dull flesh may mean the fish is old, the body should have a nice slimy coat but being dull may mean it has been wiped down with a cloth or washed.
Check the gills they should be a nice bright red and free from slime - Slime in the gills could mean bacteria so avoid fish with slimy pale gills.
The fish should smell mild, more like the sea than a fishy smell. If the fish smells fishy it has probably been there a while.
Fish fillets and steaks should be moist and without yellow or brown discoloration.
How to keep your fish fresh
A fish may be only a day old but if it is not stored correctly it might as well be a week! Fish is always best used as soon as you get it, the quicker you can use it after purchasing the better. Keep the fish cool, leaving a fish out for any length of time (even ten minutes) can loose the freshness. For every hour a fish isn't kept cool it looses a day of its shelf life!
As soon as you get your fish home gut and gill it as soon as you can, so any bacteria held in these areas cannot permeate into the flesh of the fish, then cool it in the fridge and use as soon as possible.
The best way to get fresh fish is to find a reputable fish monger, ask them what is at it's freshest. Get to know them and purchase from them regularly. Most will be happy of the regular custom and will point you in the right direction for the best catch.