Scientists invent way to make farmed salmon healthier and better for you

Telegraph

14-06-2025

Scientists have invented a way to make farmed salmon healthier.
Feeding fish with a new type of rapeseed oil, which includes a natural red pigment, makes pink seafood richer in omega-3 oils and filled with more antioxidants, a study has found.
The pinkness of a fish, whether shrimp, trout or salmon, comes from consumption of a chemical called astaxanthin, which is produced by some algae in the wild.
Wild fish eat this in their diet and become pink as a result, but farmed fish do not and as a result have naturally grey flesh.
These fish are therefore fed synthetic versions of this chemical to make the aesthetically pleasing hue consumers desire.
But a genetically modified variant of the crop, which is spliced with genes from the scarlet flax flower, creates a plant that naturally produces seeds rich in astaxanthin.
DNA, which powers the pigment-making pathway, was injected into the crop's own genome and small batches were grown at trial sites in the US and UK.
Published in the Plant Biotechnology journal, data show that in each gram of seed from this new crop, there are 136 micrograms of colourful pigments. More than a third (47 micrograms) is astaxanthin.
Giving this to fish in their diet to make them pink, instead of the current synthetic astaxanthin, would make the salmon healthier and better to eat, scientists say.
In another experiment by the same scientists at Rothamsted University, oil made from these plants was given to 120 rainbow trout in four tanks. The study was later published in the journal Aquaculture.
These animals grew just as big and were richer in health chemicals such as omega-3, the study found.
Prof Johnathan Napier, a plant biotechnology pioneer who led the work at Rothamsted, told The Telegraph: 'The plant-based source of the pigment is accumulated and delivers benefits to the fish.
'In particular, it can help reduce the build-up of pro-inflammatory molecules.
'We are also hoping to see if having diets in which the plant-derived astaxanthin is present makes them more resistant to disease (especially lice) and stress – that work is ongoing.'
The fish which eat the new oil are healthier, he said, and the humans that eat the fish are also set to benefit from the change.
Prof Napier said: 'One would hope that fish being fed this diet would be more healthy [sic],'
'Astaxanthin helps to reduce oxidation, and therefore protects the fish's metabolic state as well as protecting the healthy omega-3s and then we consume and get health benefits for ourselves.
'And there is also an additional potential benefit from having the astaxanthin in your diet, as an antioxidant.'
The scientists who invented the new plant used genetic modification techniques to create the astaxanthin-rich rapeseed oil. It is not possible to grow this crop commercially in the UK because the UK still uses the EU legislation prohibiting genetically modified (GM) foods.
GM foods are allowed in the US and Prof Napier believes fish and farmers over there will be able to benefit from this new product in less than ten years.
Red tape around the use of GM foods in UK agriculture, he believes, is stifling the market and also preventing foods which
Prof Napier said: 'Tax revenue is being used to fund millions of pounds' worth of fundamental research in UK universities and institutes.
'But the potential arising from any useful discoveries is not correctly captured or exploited because of regulatory burdens.
'In the specific example of GM crops, we are still lumbered with the EU regulations, so we are double-whammied.'