MONTHLY VARIATION OF GUT FAUNA AND FLORA OF MENI FISH (Nandus nandus) IN KAWADIGHI HAOR OF SYLHET DIVISION

Abstract

The present research was conducted to find out the monthly variation of gut fauna and flora of Meni fish (Nandus nandus) in Kawadighi haor of Sylhet division from January to December 2014. Different aspects of alimentary canal were assessed macroscopically. Gut content and histological analysis of gut were observed microscopically. From the histological analysis, Intestinal wall was composed of the tunica mucosa, tunica submucosa, tunica muscularis and tunica serosa. The tunica mucosa had many folds known as villi. The mucosal epithelium was composed of enterocytes with brush border. The mouth cavity of N. nandus was sac like elongated structure. Oesophagus was observed comparatively smallest part of the alimentary canal. Stomach was well developed, tapering and nipple form. The intestine was more or less coiling in pattern. Fish length and weight were strongly positively co-related (R =0.918) means that the total length increased significantly with the increasing of total weight. The highest value of VSI was observed at June (5.18±0.25) and lowest at October (1.86±0.12). The maximum value of HSI was observed at June (2.49±0.45) and minimum at October (1.07±0.23). The average total length was 1.06 times greater than intestinal length of fish. The intestinal length was 3.92 times greater than that of stomach. Three groups of phytoplankton were found in the gut content of N. nandus. They were Bacillariophyceae (2 genera), Chlorophyceae (6 genera), and Cyanophyceae (2 genera). Three groups of zooplankton belonging to Crustacea (9 genera), Rotifera (6 genera) and fish and insects larvae were recorded from the guts. Among various groups of phytoplankton, Chlorophyceae was observed highest in abundance. Among the zooplankton, Crustacea was dominant group. The average amount of stomach content was higher in March, July, and September compared to other months of the year. There was no empty stomach found over the study period. The research work drew a conclusion that N. nandus fed on both phytoplankton and zooplankton but showed highest preference for zooplankton.

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