Nile tilapia production (Oreochromis niloticus L.) using tree spinach leaves (Cnidoscolus chayamansa McVaugh) as a partial substitute for balanced feed

Aquaculture is an alternative for the production of high-quality, low-cost protein, particularly in developing countries with a limited food supply. In rural areas, the availability of alternative inputs is key to improving fish farming production, especially if these inputs are unprocessed. The leaves of tree spinach (Cnidoscolus chayamansa), a bush that grows in Mexico and Central and South America, are one such option. In this work, juvenile tilapia (7-14.5 g) survival, growth rates, and food conversion rates were studied during two seasons (warm and cold), substituting 25 and 50% of the balanced feed rations with raw tree spinach leaves (ad libitum). The experimental design was completely random, with two treatments and one control (100% of the balanced feed ration); three replicates were done in each season. The densities were 36 fish m(-3) per replica in the cold season and 44 fish m(-3) per replica in the warm season. The weight gain in the treatments with 50 and 75% balanced feed and tree spinach leaves was similar to that of the control group in both seasons. The cold season adversely affected survival, weight gain, and feed conversion rates in all treatments, but the warm season did not. When tree spinach leaves were included in the tilapia diet, the feed conversion rate for the balanced feed was reduced from 9.17 to 33.62% in the cold season and from 15.38 to 40.23% in the warm season. The results show that the use of locally available complementary inputs such as tree spinach leaves may favor the development of small-scale tilapia cultures in the tropics.