We examined whether individual differences in patterns of parental care relate to individual differences in situations involving novelty, risk and aggression in the convict cichlid, Cichlasoma (Archocentrus) nigrofasciatum. Individual differences in situations of novelty and risk could be summarized along two axes: Freezing versus Activity and Activity-Inspection versus Freezing. However, these...

The chromosomes of one Cichlasoma facetum and three Geophagus brasiliensis populations from the headwaters of adjacent river basins (Paraná State, southern Brazil), were investigated using differential staining techniques (C-banding, Ag-NORs, DAPI and CMA3) and fluorescent in situ hybridization (FISH) with 18S rDNA and 5S rDNA probes. The diploid chromosome number (2n) was invariably 48 in the ...

Social hierarchies are omnipresent in the lives of many species. The ability to successfully navigate complex social environments with consideration of the relative rank of conspecifics is an essential skill not only for humans, but also for numerous other social beings. From maintaining rank and reducing conflict, to communication and reproduction, organisms of varying complexity rely on socia...

Evaluating the effect of dietary soybean oil (S.O) on growth performances of juvenile ornamental fish Severum (Heros severus) was the main objective of this study. To achieve this objective, 462 fish were considered which were divided into 7 test groups including 6 groups of fishes (with an initial average weight of 0.6 ± 0.05 g and length of 2.3±0.35 cm) fed diets containing 6 levels of S.O (D...