Fish Nutrition and Feed Technologies

Development of new feed components or complete feeds

As the aquaculture sector continues to grow, so does the demand for feed and its raw materials. This leads to new challenges in the feed area, both from an ecological and an economic point of view. Increasing demand and international crises have led to rising raw material prices, which are felt throughout the entire value chain. At the same time, the use of globally available resources in fish feed affects its ecological footprint due to long transport routes and also causes socio-economical problems.

The Aquaculture@Fraunhofer community is dedicated to identifying locally available by-products of food and feed production and evaluating them for their suitability as raw materials for fish nutrition.

The community cooperates with many companies from the feed and feed raw materials sector in developing feeds with special requirements, such as the nutrition of marine fish larvae or the nutrition of fish in closed recirculation systems. 

Replacement or substitution of fishmeal and fish oil with sustainable alternatives

One of the biggest challenges in aquaculture is to find sustainable alternatives to fishmeal and fish oil in the diets of many aquaculture species.

Many of the species that are already used commercially in aquaculture naturally feed on fish, which makes this raw material the ideal basis for a diet that meets their needs. However, this has a strong negative impact on the sustainability and eco-friendliness of fish feed at the same time.

In the search for alternative raw materials, renewable, plant-based alternatives, single-cell alternatives such as yeasts or fungi as well as animal-based alternatives from by-products of the food and cosmetics industries are being investigated in more detail.

In addition to the identification of new raw materials, special attention is paid to the sustainability, compatibility and usability (digestibility and retention) of the raw materials, as well as the growth performance of the organisms in order to evaluate and, if necessary, optimize them if related problems are identified during establishment.

Research into functional ingredients such as, e.g., minerals, colorants (e.g., astaxanthin), amino acids, pro- and prebiotics and enzymes

Replacing fishmeal with alternative plant-based raw materials poses many new challenges, such as antinutritive factors in the form of plant stores for minerals, plant antifeedants against pests and other plant-based components to which aquatic organisms would not be naturally exposed from an evolutionary perspective.

For example, certain storage forms of minerals cannot be broken down by the fish's digestive system, as the required enzymes are not available in the fish's digestive “construction kit.” As a result, certain minerals have to be added to the feed, even though they are sufficiently available in the plant source, to meet the requirements of the respective species.

To make fish feed as resource and environmentally friendly as possible, such “overdosing” must be avoided.

Therefore, one research focus of the community is on the use of enzyme additives to increase the usability and digestibility of plant-based raw materials as well as the use of functional feed components to improve the compatibility and utilization of plant-based raw materials. 

Determination of the micro- and macronutrient requirements of species already used in aquaculture or to be newly established

Compared to traditional agriculture, the potential of usable animal species is far from exhausted. The diversity of animal organisms used in aquaculture far exceeds that of classical agriculture.

There is much less validated knowledge about the species already used in aquaculture than for the “big four” of agriculture (pigs, cattle, poultry, sheep).

For many economically interesting aquaculture species, such as eel or tuna, it has not even been possible to fully close their life cycle in production.

This is often due to a lack of knowledge regarding the exact micro- and macronutrient requirements of the different life stages of the respective species.

The Aquaculture@Fraunhofer community is devoted to research in this area in order to close these knowledge gaps and thus enable a more sustainable and animal-friendly production of these species. Among other things, the research focuses on the need for certain minerals, essential amino acids and essential fatty acids of various aquaculture-relevant species.