Inclusion of near-threatened micronutrient-rich small indigenous species (SIS) dhela (Osteobrama cotio) in pond aquaculture

Due to their high content of micronutrients, small indigenous species (SISs) of fish play a vital role in the diets of people. Dhela (Osteobrama cotio) is one of the most important micronutrient-rich SISs and was once abundant but is currently disappearing from inland waters. This study investigated the culture suitability of dhela with carp species in polycultures in a pond aquaculture system. The stocking density of the carp species was the same in all the treatments, with Labeo catla, Labeo rohita and Cirrhinus cirrhosus at 10,800/ha. Dhela were cultivated at a density of 10,000/ha in treatment 2 (Dhela-10K) and 15,000/ha in treatment 3 (Dhela-15K), and no dhela were cultivated in treatment 1 (Dhela-0). After 7 months of culture, there were no significant differences in total production among the treatments, with yields of 3393.27 ± 120.70, 3534.52 ± 57.03 and 3687.34 ± 244.41 kg/ha in Dhela-0, Dhela-10K and Dhela-15K, respectively. Notably, a significantly greater (p < 0.05) net profit and benefit‒cost ratio were found in Dhela-10K and Dhela-15K than in Dhela-0, but no significant difference was found between Dhela-10K and Dhela-15K. The inclusion of dhela in pond polycultures with carp species demonstrates the potential benefits of diversifying aquaculture systems. Farmers could consider incorporating SISs into their existing aquaculture practices to increase overall production and improve economic returns.