Notes on the natural diet and habitat of eight danionin fishes, including the zebrafish Danio rerio
The diet and habitat of eight danionin species (Danio and Devario) from 18 sites in India and Thailand are reported. At every site, habitat characteristics, including pH, light penetration, water temperature, current speed, stream dimensions, canopy cover and substratum type, were recorded. Danionins were found primarily in warm (24–35° C), moving water of moderate clarity and pH (6·6–8·2) and there were significant differences among species in water temperature, pH and current speed. Deep-bodied Devario species were generally associated with faster water currents than more slender-bodied Danio species. Gut content analyses of 327 individuals representing 17 populations showed that insects were the primary food resource for the eight Danio and Devario species. Crustaceans, fish scales, algae and detritus were also important supplements for particular species. Stable isotope data from syntopic species indicated long-term differences in consumption of terrestrial v. aquatic insects in one of two population pairs.
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