Aquaponics systems integrate fish and plant culture, relying heavily on nutrients derived feed, typically fish meal, which is expensive and scarce. This study investigates the use of Niger seed cake as a replacement for fish meal and its impact on anion dynamics within a Nile tilapia-lettuce aquaponics system. Five experimental treatments were tested. Overall, the study demonstrated that Niger seed cake can effectively replace fish meal in aquaponics systems with minimal impact on anion dynamics, making it a viable, sustainable alternative protein source.
Fishmeal is a good protein source that could help the performance of fish because it has high protein source. But, it is very expensive to afford for developing countries like Ethiopia (Akewake Geremew et al, 2015). So, replacement of fishmeal with cheaper ingredients of plant origin in fish feed is necessary. Niger Guizotia abyssinica belongs to the family Compositae and the genus Guizotia, has only six species, of which five are native to Ethiopia (Baagoe, 1974). It is one of the sources of edible oil. The waste after oil extraction is free from any toxic substance and contains approximately 30% protein and 23% crude fibre (Getinet and Sharma 1996). According to Rumsey (1993), increased use of plant protein supplements in fish feed can reduce the cost of fish meal. According to Abebe Tadesse (2017), the proportion of Niger seed cake should not be more than 45%.