Monthly analysis of gut content of near- threatened Nandus nandus (Hamilton, 1822) at Kawadighi Haor in northern Bangladesh

The successful fish species culture is correlated with the profound analysis of the food and feeding habits of that species. This research aimed to address the monthly variation in the gut contents of Nandus nandus. A total number of 108 specimens were collected from Kawadighi Haor in Sylhet division, Bangladesh from January to December 2014. Four taxa of zooplankton were identified, belonging to Crustacea (9 genera), Rotifera (6 genera), larvae (2 genera), and tiny fish and small prawns (3 genera), in addition to three classes of phytoplankton viz. Bacillariophyceae (2 genera), Chlorophyceae (6 genera), and Cyanophyceae (2 genera) were recorded from the guts. Crustacea (6.00±0.62×10³ units/l) showed the dominant group among the zooplanktons, while Chlorophyceae (3.14±0.49×10³ units/l) was the most abundant among phytoplanktons. The average index of gut fullness recorded its highest in March (3.67) and the lowest in December (2.11). All fish were actively fed during the whole year, and the percentage of empty guts was almost non-existent. Based on the present findings, zooplankton was the most preferred feed for N. nandus although it fed on both phytoplankton and zooplankton. The current data provide comprehensive data that would support the management and conservation of the species under study through the domestication of the near-threatened N. nandus in the open waters of Bangladesh, paving the way for aquaculture in captivity.