Abstract
This investigation presents the food and feeding activity of and endangered riverine catfish Rita rita, during February 2017-January 2018. A total of 225 fish individuals was analyzed for stomach contents by characterizing the dominant food items and morphometric features. The results divulged ten major food items consumed, preferably fish scales and eggs, teleost fishes, copepods, cladocerans, rotifers, and mollusks. Total length and body weight of fish varied between 9-34 cm (20.53 ± 6.90 cm) and 10-400 g (9125.94 ± 102.07 g), respectively. The index of relative importance (IRI%) showed the importance of rotifers over the other food items. Morisita's index of diet overlap indicated seasonal variations in catfish diets with summer and monsoon displaying the least overlap, while maximum overlap during monsoon and winter seasons. The non-metric multidimensional scaling (nMDS) indicated the close association between the food items available during summer and winter seasons with a significant difference among the seasons (ANOSIM, R = 0.638, P = 0.013). Levin's niche breadth index arranged in the order of 0.88>0.81>0.78>0.63>0.43 for the size classes of V, IV, III, II and I, respectively. The PCA explained 95.39% of the total variance among the food items and fish size groups. Small-sized fish individuals displayed a greater correlation with food items suitable for their mouth size. In conclusion, the variety and frequency of food items recorded indicated considerable feeding plasticity and opportunistic feeding behavior with a shift from carnivorous to omnivorous feeding nature. This study could render useful information on the food and feeding habits of R. rita and provide background for preparing its diet for future aquaculture practices.
Highlights
Investigations on feeding habits and preferences provide essential data on the trophic interactions and nutrient flow in the aquatic ecosystems (Fatema et al, 2013; Campos et al, 2015; Atique and An, 2018, Atique et al, 2019; Saeed et al, 2020; Rahman et al, 2020) as the success of a fish species in its typical habitat is associated with its diet because it provides crucial insights into its natural history (Braga et al, 2012; Batool et al, 2018; Kim et al, 2019; Iqbal et al, 2017a, 2020; Khanom et al, 2020)
The examination of stomach contents of 225 individuals of R. rita resulted in the identification of 10 major food items, including fish scales, fish eggs, teleost fishes, copepods, cladocerans, rotifers, insects, mollusks, plant materials, and mud and sand particles (Table 1)
IRI% value of fish scales and teleosts were found higher during the summer season as well as in the fish size group >29-34 cm
Summary
Investigations on feeding habits and preferences provide essential data on the trophic interactions and nutrient flow in the aquatic ecosystems (Fatema et al, 2013; Campos et al, 2015; Atique and An, 2018, Atique et al, 2019; Saeed et al, 2020; Rahman et al, 2020) as the success of a fish species in its typical habitat is associated with its diet because it provides crucial insights into its natural history (Braga et al, 2012; Batool et al, 2018; Kim et al, 2019; Iqbal et al, 2017a, 2020; Khanom et al, 2020). Changes in dietary preferences of a fish species largely depend on the availability of preferred prey items in the associated environment. An abundance of favorite prey items in the environment regulates their predominance of food items in the fish stomach (Palmeira and Monteiro-Neto, 2010; Gondal et al, 2020; Kim et al, 2021). Analysis of stomach contents based on the seasonal and morphological traits could help in establishing standard practices in fishery science and could provide relevant scientific advice on sustainable fisheries management (Hyslop, 1980; Zacharia, 2004)
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