To some, aquaculture (farmed fishing) may appear to be a practical alternative to the inherently exploitive practices of commercial fishing. In reality, aquaculture further threatens wild populations and their fragile ecosystems. While commercial fishing indiscriminately destroys entire ecosystems, aquaculture does to the oceans what industrial animal factories do to the land.
The aquaculture industry is growing more rapidly than any other sector of industrial animal farming. Approximately 50% of all the fish killed for food in the world are raised in these confined offshore systems.  Increasingly, the aquaculture industry is relying on wild caught fish to feed the fish they are raising for public consumption. Between 1992 and 2006, the volume of fishmeal and fish oil used for aquaculture feed has tripled.  In 2006, aquaculture feed used 56% of the world’s fishmeal and 87% of all fish oil. 
Each year, 5-6 million tonnes of “trash fish” are also used to produce aquaculture feed.  These fish are commercial by-catch and are considered too low quality for human consumption. Now that these fish have an increased value to the industry, commercial fishermen are finding indiscriminate methods of capture more lucrative than ever before.
The industry knows that its reliance on commercial fishing is highly unsustainable. They acknowledge the fact that using wild caught fish to feed farmed fish is highly inefficient; however, their solution to this problem is even more disturbing. Aquaculture feeds are increasingly utilizing proteins from grains such as soybeans and wheat, as well as meat meal and poultry meal from industrial animal factories. 
In addition to its reliance on commercial fishing as a source of supplemental feed, aquaculture also threatens the genetic integrity of wild populations. Many farmed species have been artificially interbred-such as the GIFT (“Genetically Improved Farmed Tilapia”). According to the United Nations Food and Agricultural Organization:
“It appears inevitable that, either through deliberate stocking or through escapees, individuals from a composite population (which has been further modified through the domestication process) will eventually re-enter the natural environment inhabited by the parent stocks. Such introductions may result in the genetic breakdown of wild stocks and the loss of unique reservoirs of genetic diversity for the species.” 
 Retrieved 9/27/09 from http://www.fao.org/fishery/sofia/en
 Retrieved 9/28/09 from http://www.crawfordfund.org/assets/files/conference/proceedings/fish_aqua_food.pdf