A team of Ph.D. students from Mendel University in Brno is searching for new uses for fish farming waste. They are developing FISHIT, a biostimulant made from fish sludge that promotes plant root growth, improves nutrient uptake, contributes to plant growth and vitality, and increases plant resilience. The project brings together experts from MENDELU’s Faculty of AgriSciences and Faculty of Horticulture and could benefit both gardeners and farmers in the future.
The idea for the project originated more than two years ago through the integration of research topics pursued by Ph.D. students at Mendel University. While Kateřina Patloková from MENDELU’s Faculty of Horticulture focuses on optimizing plant nutrition in hydroponic systems and the use of biostimulants, Lukáš Harabiš from the Faculty of AgriSciences is investigating ways to process fish sludge, a byproduct of intensive fish farming. “Fish sludge contains organically bound nutrients as well as a natural microbial component, and it would be a shame to view it merely as waste. We therefore began looking for a way to convert it, through a controlled process, into a liquid preparation that can be used in plant cultivation,” explain the project authors.
The research is being conducted primarily at the Department of Fisheries and Hydrobiology at MENDELU’s Faculty of AgriSciences, which includes recirculating aquaculture systems. The research team first identified the optimal method for breaking down the waste (sludge) generated in these recirculating systems using oxygen and microorganisms. Another key issue was verifying the effectiveness of the resulting product. The first large-scale testing was conducted on hydroponically grown watercress, where part of the standard mineral fertilizer was replaced with the fish sludge-based product. The plants achieved a yield comparable to that of standard mineral nutrition, but at the same time developed a significantly larger root system—40.3% larger than the mineral control.
The results thus suggested that this was not just another liquid fertilizer. The product also exhibited a biostimulatory effect, which was further investigated in terms of microbiology and the content of biologically active substances. A larger root system, together with the beneficial microorganisms and biologically active substances in the product, can improve plants’ uptake of water and nutrients, promote their growth, and increase their resistance to stress factors. The original experiment was therefore followed by a series of additional growth tests. In a pot experiment with basil, plants treated with the highest tested concentration of the product achieved, on average, 27% higher above-ground biomass weight than control plants watered only with water. “A statistically significant effect was also confirmed for the variant with the sterilized product, suggesting that not only the microorganisms present but also the biologically active substances naturally present in the product contribute to its effect,” said Harabiš.
Further testing was conducted on a wide range of plants, including leafy, root, bulb, and fruit vegetables, small fruits, and ornamental plants. Based on the results of these experiments, optimal application methods and dosages were proposed for individual crop groups, which will subsequently be listed on the product label.
As the project progressed, the researchers began exploring the commercial potential of their research findings, leading to the creation of the FISHIT brand, whose name reflects the product’s origin. The research team is currently collaborating with the Tilapia s.r.o. fish farm, which allows them to test the technology outside the laboratory setting and focus on the practical aspects of future production. In the coming months, the team will focus primarily on monitoring the reproducibility of the process and the stability of individual production batches under actual operating conditions.
The product is suitable for a wide range of plants grown in open soil as well as in containers. It is intended for application as a soil drench or foliar spray and can be used for rooting cuttings as well as a supplement in hydroponic systems. Thanks to its 100% natural origin, it can also be used in organic farming.
Another significant step for the research team was participating in the MENDELU Boost competition, which supports the transfer of research results into practice. In addition to developing the product itself, the team also began addressing issues related to brand protection, the future business model, pricing, distribution, and marketing. “FISHIT is no longer just a working title for an experiment written in marker on a barrel. It’s a functional product backed by university research, and now we’re figuring out how to get it from the lab to growers,” added Patloková.