Not only fish, but advancements in aquaculture in recent years are giving us mussels, crabs and other shellfish.

Aquaculture is the raising of water-residing livestock. This allows the taste and size of the yummy creatures in question to be controlled. In some cases (like mussels) the farmed variants are of higher quality (as a food) than the wild variety. (in the case of mussels you end up with a thinner shell and larger meat, catfish are not as "muddy" tasting and contain fewer parasites).

Aquaculture is also a boon to the environmentalist movement. Most aquacultural methods have minimal impact on the environment, and indeed aquaculture is being used to preserve the wild populations of certain species (such as salmon). Also, new architectual designs of breeding and holding tanks use up less land and resources than the raising of cattle or sheep.

Aquaculture is currently a growing industry but it will provide us with cheaper seafood (something I am all for).

If anyone can give me some downsides to aquaculture I'd love a "couterpoint" posted here