Mycoprotein in enhancing growth and immunity of fish

Abstract Mycoprotein, a protein source derived from fungi, is being researched more and more in aquaculture for its ability to promote fish health, especially immunity, growth, and resistance to disease. With high levels of essential amino acids and bioactive substances, mycoprotein offers a high-quality protein that promotes optimal growth and muscle development in fish. In addition to its nutritional quality, mycoprotein has great health benefits, especially in boosting the immune system. It enhances the fish's immune system by activating the primary immune cells, including macrophages and lymphocytes, which are responsible for countering bacterial, viral, and parasitic infections. The bioactive ingredients in mycoprotein also enhance mucosal immunity, an essential first line of defense against pathogens entering the body. Besides improving the immune system, mycoprotein is also key in mitigating fish stress levels that can negatively impact health and productivity. Mycoprotein has been associated with reduced cortisol levels in some trials, suggesting potential stress-mitigating effects. Such associations may contribute to improved resilience and overall well-being of fish in aquaculture, although direct evidence for modulation of cortisol synthesis is lacking. This reduction of stress translates into increased growth rates and health status because chronic stress weakens the immune system and causes fish to become more disease-susceptible. In addition, mycoprotein aids in maintaining intestinal well-being through maintaining a balanced population of beneficial microbiota necessary for proper digestion and nutrient utilization. An effective gut enhances fish nutrient usage and supports improved immune response, making fish less susceptible to gastrointestinal disorders. This article is a review that synthesizes current research on mycoprotein and evaluates its role in enhancing fish immunity, promoting growth performance and improving disease resistance. The objective is to critically examine existing evidence, highlight knowledge gaps, and discuss the potential of mycoprotein as a sustainable and functional aquafeed ingredient for healthier aquaculture systems. Mycoprotein provides a diversified strategy for promoting fish health, with evidence of immunostimulation, growth support, and enhanced pathogen resistance in several aquaculture species. However, these effects are dose-dependent and species-specific, and variation exists depending on fungal strain and processing method. As a replacement for conventional protein sources such as fishmeal, mycoprotein offers a viable solution for controlling disease outbreaks and enhancing fish health in aquaculture, enabling more robust and efficient farming methods.