Melanin spots, or “black spots,” in Atlantic salmon fillets have long been a source of concern for the salmon farming industry, contributing to product downgrades, increased processing costs, and significant financial losses.
A recent report by the Norwegian University of Environmental and Biosciences (NMBU) linked these dark spots to changes in the fish’s fatty tissue. The condition, referred to as “fat necrosis,” occurs when the immune system reacts to dying fat cells, which in turn release fat that accumulates in the muscles, leading to chronic inflammation.
The report also identified a potential cause: the high levels of vegetable oils used in salmon feed. These oils contain excessive polyunsaturated fatty acids and insufficient saturated fats, which researchers believe may contribute to fat necrosis in salmon, similar to what is seen in other animals.
New report links vegetable oils in feed to black spots on salmon
With melanin spots affecting up to 30% of fish in some regions, particularly in Norway and Chile, the economic toll on the industry is considerable. The Norwegian Fisheries and Aquaculture Industry’s research funding (FHF) has called for the industry to use this new knowledge to review feed formulations and implement changes.
Enter Aker BioMarine, a supplier of krill-based ingredients, which now claims its product, QRILL Aqua, could be a viable solution to the problem. According to Aker BioMarine, including krill in salmon feed may not only address the root cause of melanin spots but also improve overall fish health and yield.
A new approach
QRILL Aqua, a krill-based feed ingredient from Aker BioMarine, is rich in essential omega-3 fatty acids—specifically EPA and DHA—known for their anti-inflammatory properties. These fatty acids are delivered in a phospholipid form, which Aker BioMarine claims is more easily absorbed by fish than those found in vegetable oils.
The company points to recent trials showing that the inclusion of 7.5% QRILL Aqua in salmon diets has reduced the severity of melanin spots in fish weighing between 1.2 and 3.2 kg. By improving the fish’s ability to regulate inflammation, Aker BioMarine argues that krill-based feed could effectively prevent the accumulation of melanin pigments.
Internal research from Aker BioMarine also suggests that the benefits of QRILL Aqua extend beyond just reducing melanin spots. Trials have shown improvements in feed intake, growth performance, lower mortality rates, and overall fish robustness—factors that contribute to higher quality salmon fillets and, in turn, a better economic return for farmers.
