FishPlant

Overfishing is leading to a drastic decline in fish stocks, endangering marine biodiversity. The loss of key species can destabilize ecosystems and disrupt food webs. Fishing businesses in particular suffer a considerable loss of income due to overfished waters and see their economic existence threatened. Last but not least, a lack of fresh fish also jeopardizes food security.

More and more fish are being bred in controlled offshore aquacultures - i.e. in specially constructed breeding cages “off the coast”. However, such aquacultures can significantly disrupt neighboring marine ecosystems and even destroy habitats. Furthermore, the migration of non-native fish species can threaten native species, while wastewater and feed residues from aquaculture can pollute waters and affect water quality. In addition, offshore aquaculture results in higher transportation costs and CO2 emissions, as the products often have to be transported over long distances.

FishPlant aims to counteract these problems by developing closed, recirculating onshore aquaculture systems (RAS). In contrast to offshore aquacultures, these protect marine ecosystems and wildlife habitats, promote biodiversity and prevent overfishing.

A combination of fish farming and hydroponic plant cultivation

The main objective of FishPlant is to improve the profitability of RAS plants by simultaneously producing marine fish and salt-resistant food plants (halophytes). Here, the cultivation of sea bream is combined with the hydroponic cultivation of sea asparagus (Salicornia). Hydroponics is a type of plant cultivation that uses water enriched with nutrients rather than soil. This creates a resource-efficient, sustainable closed-loop system: the nutrient-rich, saline wastewater and the CO2 produced from fish farming are used for plant production, while excess heat and the O2 produced by the plants flow back into the fish culture. This dual production promotes an optimal value chain and ensures a high level of profitability.

We use our specially developed and patented vertical farming technology OrbiPlant® for plant cultivation in the project. The system uses an aeroponic irrigation system that supplies the plants with water and nutrients in a targeted manner using integrated nozzles. A major advantage of this is the minimized water consumption, which creates far more environmentally friendly production conditions in which the use of pesticides is completely avoided and only a small amount of fertilizer is used.

In FishPlant, sea asparagus is grown in the OrbiPlant® system. It is a salt-resistant plant that grows naturally in coastal regions and has only been discovered as a valuable food plant in recent years. Sea asparagus has fleshy, green shoots that are rich in vitamin C and minerals such as iron and potassium. Its ability to thrive in salty environments, in combination with fish production, makes it an ideal candidate for cultivation in aquaculture. Its taste is salty with a tangy-sweet note and falls into the “umami” category, making it a versatile ingredient in the food industry.

"In the Netherlands, sea asparagus is already available in many supermarkets, but in Germany, interest in sea asparagus is only just picking up speed. As it is rich in vitamins, minerals and antioxidants, sea asparagus is considered a real superfood. Its salty-spicy flavor profile makes it an aromatic ingredient in food, both raw in salads or cooked as a side dish. I therefore see a market niche for sea asparagus with great economic potential, especially in combination with the production of sea fish," explains Dr. Marc Stift, Group Leader Vertical Farming at Fraunhofer IME in Aachen.

In the project, Fraunhofer IME in Aachen is working together with the fish producer Aixponic GmbH, which is also based in Aachen and is responsible for sea bream farming in the project. The local production of fish and marine vegetables reduces the dependence on imported food, which is a big advantage for urban areas such as Aachen, where access to fresh food - and particularly fresh sea fish - is limited. Long transportation routes and high logistics costs are minimized by regionality, as are the associated CO2 emissions. The project therefore not only pursues economic goals, but also actively contributes to ecological sustainability and to improving the food supply in urban and arid areas.

The FishPlant project started in January 2025 and is funded by the German Federal Ministry of Food and Agriculture.