More and more fish are being raised on farms before they end up on dinner plates around the world. Aquaculture, or the culturing of fish in a controlled environment, now accounts for 50 percent of the fish consumed globally, a fact that's putting tremendous strain on wild fish.

    The big downside to fish farming: It requires large amounts of feed made from wild fish harvested from the sea.

    There are also concerns about spreading disease from farmed to wild fish.

    Nonetheless, fish farming has grown rapidly in recent years, nearly tripling in volume between 1995 and 2007. Part of the reason for the rise is increased demand for omega-3 fatty acids, a type of fatty acid found in oily fish that is thought to be effective in reducing the risk of cardiovascular disease, according to the National Institutes of Health.

    In order to maximize growth and enhance flavor, aquaculture farms use large quantities of fishmeal and fish oil made from less valuable wild-caught species, including anchoveta （cousins to anchovies） and sardine. In fact, 88 percent of global fish oil consumption goes to aquacultures.

    This adds up to quite a lot of fish being used for fish food. In 2006, about 22 million short tons （20 million metric tons） of wild fish were needed to produce 57 million short tons （51.7 million metric tons） of farmed fish.

    Fishmeal and fish oil are especially important for raising carnivorous fish, including salmon, trout and tuna. "Vegetarian" fish, on the other hand, can be raised on feed made from plants.

    Several legislative acts call for the reduction of fishmeal and fish oil in feeds, including California's Sustainable Oceans Act and the proposed National Offshore Aquaculture Act.

    在世界各地，越來越多的魚，在它們于餐盤上告罄之前，正在養殖場內不斷增加。水產業，或者在一個受控環境進行的魚的養殖，現在已經占有全球范圍內消費 的魚的 50%.這是一個把巨大壓力加到野生魚類上的事實。

    魚類養殖的大的消極面是：它需要大量從大海捕獲的野生魚所制成的飼料。

    也擔心從飼養的魚向野生魚類傳播疾病。

    盡管如此，魚類養殖近年來還是迅速增長，1995 年至 2007 年，在數量上幾乎增加三倍。部分原因是對歐米伽-3 脂肪酸的需求增加。根據美國國家衛生研究院的說法，歐米伽-3 脂肪酸是在含油多的魚類中發現的一種脂肪酸，被認為在降低罹患心血管疾病的風險方面有效。

    為了得到最高的產量并且增強滋味，水產養殖場使用大量的由低價值的野生魚種，包括秘魯鳀魚（鳳尾魚的表親）和沙丁魚制成的魚粉和魚油。事實上，全球 88% 的魚油消耗量去往水產養殖。

    這意味著相當多的魚正被用于魚飼料。2006年，需要大約 2200 萬短噸（2000萬公噸）野生魚來生產 5700 萬短噸（5170 萬公噸）養殖的魚。

    魚粉和魚油對于飼養食肉性的魚類，包括鮭魚、鱒魚和金槍魚尤為重要。另一方面，"素食"的魚，可以用植物做成的飼料來喂養。

    有幾個立法法案要求減少飼料中的魚粉和魚油，包括加州的《可持續發展的海洋法案》和建議的《全國海洋養殖法案》。