Topic: Feed and nutrition

Fish can suffer nutrient deficiencies

In their natural environments, fish eat everything from small prey in rivers and the sea to bigger animals like fish and crustaceans. But farmed fish, which live their whole lives in cages, eat dry feed in the form of pellets. Each pellet is a packed lunch containing the nutrients needed by the fish: fats, proteins, carbohydrates, vitamins and minerals.

If a fish gets too little of important nutrients, it may develop diseases. For example, if it doesn’t get enough of the amino acid histidine, it may develop cataracts in its eyes. And if the fish gets too little of certain vitamins or minerals, it may develop fatty liver and bone deformities. Being given the optimal feed will also help farmed fish to cope better with stress.

New feed ingredients

Fish feed was traditionally composed of fish oil and fish meal, but in recent years many of the marine ingredients have been replaced with plant-based ingredients, such as rapeseed oil. One result of this is that farmed salmon contain less marine omega-3 fatty acids than in the past, but research shows that they are still a good source of these fatty acids.

Nevertheless, if we want to further expand aquaculture in the future, there is a need to find new, good raw ingredients for fish feed. One alternative may be to replace fish meal with insect meal. When researchers replaced traditional fish meal with insect meal, they found that the fish grew just as well, and tasted just as good. A tasting panel was unable to detect any difference between the fish given feed containing insect meal and those that were given fish meal.

How we monitor fish feed

The Norwegian Food Safety Authority has tasked the Institute of Marine Research (IMR) with monitoring fish feed each year. The Food Safety Authority takes samples from feed producers and factories across Norway at different times of the year. The IMR analyses the feed and the ingredients it contains, including both marine and plant-based ones, for their levels of nutrients and unwanted substances. The aim is to obtain a representative selection of fish feed and feed ingredients that are used in Norwegian fish feed production, and thereby map potential threats from fish feed to public health, fish health, fish welfare and the environment.

Norway follows EU rules on animal feed, which means that its legislation is regularly changed and updated in line with EU rules. The results of our monitoring activities can be found in our annual report on monitoring fish feed on hi.no.