Nutritional composition of water hyacinth diets for fish

Abstract

The rising cost and limited availability of conventional feed ingredients such as fishmeal pose a significant challenge to sustainable aquaculture, especially in developing countries. This study investigated the potential of water hyacinth (Eichhornia crassipes), an invasive aquatic plant, as a costeffective alternative in fish diet formulations. Five experimental diets were formulated by progressively replacing fishmeal with water hyacinth leaf meal at 0%, 25%, 50%, 75%, and 100% inclusion levels, respectively. Proximate analyses were conducted to determine moisture, ash, crude protein, crude fibre, lipid, and carbohydrate contents using standard AOAC methods. Results showed that water hyacinth inclusion significantly influenced the nutritional profile of the diets. Diets with higher water hyacinth content exhibited increased ash and crude fibre levels, indicating a rich mineral composition and high fibre potential. However, crude protein content decreased with higher inclusion levels of water hyacinth, with the highest protein value recorded in the fishmeal-based diet. Lipid levels were generally low across all treatments, particularly in diets with high water hyacinth proportions. Carbohydrate content remained moderately stable across all formulations, with a slight increase in the highest inclusion level. The study concludes that water hyacinth possesses promising nutritional attributes that could complement traditional fishmeal, particularly as a mineral and fibre source. However, its low protein and lipid contents may limit its use as a sole feed ingredient. Therefore, its optimal application lies in partial replacement strategies that balance nutritional adequacy with cost-effectiveness. This work highlights the potential for converting an ecological burden into a valuable input in sustainable aquaculture feed development.