RAW MATERIALS

European Bioethanol: Its co-products, an alternative to raw materials in aquaculture

Spain, 15 September 2025 | Biorefineries across Europe generated 6.9 million tonnes of protein-rich co-products in 2024 — enough to produce over 20 million tonnes of aquafeed for seabass, seabream and meagre

Silos agricultura

In Europe, renewable ethanol production is no longer just about supplying biofuel. Increasingly, it is emerging as a source of high-protein ingredients for aquafeeds, opening the door to a more circular and sustainable food system.

In 2024, European ethanol biorefineries produced around 5.41 million tonnes of ethanol, alongside more than 6.92 million tonnes of food and feed co-products — meaning that nutritional output actually exceeded fuel output.

These co-products include dried distillers’ grains with solubles (DDGS) and high-protein variants (HP-DDG), the material that remains after starch fermentation of cereals. Rich in protein, fibre, lipids, minerals and vitamins, they can be used in both animal and aquaculture feeds.

Recent studies, reported by misPeces, highlight how these co-products can be incorporated into diets for key marine species such as European seabass (Dicentrarchus labrax), gilthead seabream (Sparus aurata) and meagre (Argyrosomus regius).

In one trial, researchers in the UK and Egypt tested high-protein variants from ethanol biorefineries in seabass grow-out diets. By supplementing feed with the enzyme phytase, which counteracts the anti-nutritional effects of phytic acid, they achieved improved nutrient absorption and growth performance.

Other studies showed that including fermented DDGS in European seabass diets significantly enhanced the digestibility of protein, lipids, starch and energy compared with non-fermented DDGS, leading to better nutrient uptake and growth outcomes.

Although fewer trials have so far been published for gilthead seabream and meagre, projects such as PISCIBIEN in Spain are exploring functional diets and welfare strategies for these species. Such work paves the way for incorporating ethanol co-products as cost-effective protein sources in future formulations.

According to both scientific studies and European production data, the potential for integrating these raw materials into aquafeeds is substantial. For seabass, gilthead seabream and meagre, a realistic scenario is that around two-thirds of the 6.92 million tonnes of ethanol co-products — roughly 4.5 million tonnes — are of sufficient quality for high-value aquafeeds. If incorporated at an inclusion rate of about 20 per cent, as trials suggest is feasible with fermentation or enzyme supplementation, this would yield enough raw material to produce 22–23 million tonnes of formulated aquafeed.

In practical terms, that volume of feed could sustain the production of 14–16 million tonnes of farmed fish, assuming a feed conversion ratio (FCR) of 1.4–1.6. These figures highlight not only the scale of the opportunity, but also the prospect of ethanol biorefineries becoming a cornerstone of a more circular and resource-efficient model for European aquaculture.

For European aquaculture species, the integration of DDGS and HP-DDG — particularly when fermented or supplemented with enzymes — represents a realistic pathway to lower costs, enhance sustainability and close the nutrient loop between crops, renewable energy and food production.