Evaluation of three commercial aquaculture feeds for use in aquaponic production of tilapia and lettuce

Abstract

We evaluated three commercial aquaculture feeds—manufactured by Zeigler Bros., Inc.; Star Milling Co.; and Cargill Animal Nutrition—for their suitability in the culture of Nile Tilapia Oreochromis niloticus and lettuce Lactuca sativa in an aquaponic system. Additionally, we assessed the yield and nutrient composition of three heat-tolerant lettuce varieties—muir (batavia/loose-leaf), crispino (iceberg), and salvius (romaine)—in response to nutrients derived from the commercial fish feed. The study was conducted in a greenhouse using six identical pilot-scale aquaponic systems, with two replicate systems per diet. Nile Tilapia with an initial mean weight of 681.1–694.9 g were cultured for 49 d. Results showed no significant differences among treatments in fish growth performance, including weight gain (188.4–221.5 g), specific growth rate (0.22–0.65%/d), feed conversion ratio (1.97–2.67), and survival (78–97%). Whole-body proximate composition (except ash) and amino acid composition of the tilapia also did not differ significantly among treatments. Similarly, the wet and dry weights of lettuce, as well as total production data, showed no significant difference. Mineral content analysis of the lettuce varieties revealed no significant differences except for the sodium level in crispino lettuce and the phosphorus and zinc levels in muir lettuce. The findings from the current study recommend that all three commercial tilapia aquaculture diets are equally suitable for use in aquaponic systems.