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Scientists take fish out of fish food

Staff writer |
It's one of the great environmental ironies of aquaculture – although the fish themselves come from farms, the food that they're raised on still contains wild-caught fish.

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A few years ago, however, a study showed that prawns could be fed microbes instead of fish byproducts. Now, a more recent study has concluded the same thing about tilapia, one of the most farmed fish in the world.

Ordinarily, fish meal and fish oil are included in commercial feeds in order to help fish grow large, and to do so quickly. When it comes to the oil, though, scientists from Dartmouth College have found that the marine microalgae Schizochytriumworks even better.

In lab tests, juvenile Nile tilapia were given a food containing dried Schizochytriumin place of the usual fish oil. When compared to a control group being raised on regular food, they were found to exhibit higher weight gain and better food-to-growth conversion, plus their flesh was higher in healthy omega-3 fatty acids.

Vegetable oils have previously been put forward as a fish oil alternative, although they don't result in such high omega-3 levels.

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