Patterns of prey selection in rohu (Labeo rohita) and singhi (Heteropneustes fossilis) larvae under light and dark conditions
1993; Elsevier BV; Volume: 118; Issue: 1-2 Linguagem: Inglês
10.1016/0044-8486(93)90283-5
ISSN1873-5622
AutoresNandita Mookerji, T. Ramakrishna Rao,
Tópico(s)Fish biology, ecology, and behavior
ResumoAbstract The prey size and prey type selectivity in the planktivorous larvae of rohu ( Labeo rohita ) and singhi ( Heteropneustes fossilis ) of different ages were tested under light and dark conditions using Bartell's “S” and Manly's “α” indices, respectively. Rohu and singhi showed essentially similar prey selectivity patterns, although as adults they occupy different food niches. These patterns did not differ substantially under light and dark conditions. When offered a choice of three rotifer species at 6 days of age, rohu actively selected Brachionus calyciflorus while singhi preferred the substratum-associated B. patulus , but both avoided the smallest-sized B. angularis . When offered different sizes of the same prey type, both fish species chose the numerically most abundant size. When the choice was among rotifers, cladocerans and copepods, the larvae showed a distinct preference for the cladoceran. Though physically capable of capturing the evasive rotifer, Hexarthra mira and copepod, Heliodiaptomus contortus , both rohu and singhi rarely included them in their diet when the medium had an alternative non-evasive prey type. The observed prey selection patterns are explained in terms of profitability and the implications for rearing the larvae in aquaculture are discussed.
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