EATING seafood these days comes with a catch.

With three-quarters of the world's oceans overfished or fished right up to their limits and 18 out of the 98 fish stocks assessed by the federal government considered as ''overfished'' or ''subject to overfishing'', buying is becoming harder for those concerned with sustainability.

On ice ... overfishing has put many fish on the threatened species list. Credit:Jacky Ghossein

Last month Greenpeace released a damning study of canned tuna brands sold in Australian supermarkets. It found most were poorly labelled or contained overfished species such as yellowfin.

The best fish to eat, according to conservationists, are species that reproduce quickly, are still in good supply and are caught using methods that minimise by-catch and damage to the ocean floor.