Body condition indices for Brycon amazonicus (Spix & Agassiz, 1829) e Colossomoma macropomum (Cuvier, 1818) in Amazon

Abstract

A study comparing the relative condition factor (Kn), splenosomatic index (SSI) and hepatosomatic index (HSI) was carried out in juveniles of Brycon amazonicus (matrinxã) and Colossomoma macropomum (tambaqui). Individuals of both B. amazonicus and C. macropomum, ranging from 18.0 to 38.0 g and 14.0 to 79.0 g respectively, were provided by the Department of Aquaculture, National Research Institute of the Amazon (INPA, Manaus, Brazil). The Kn was very similar and varied from 0.90 to 1.10 for B. amazonicus and from 0.79 to 1.25 for C. macropomum. The splenosomatic index was higher (p<0.05) in C. macropomum than in B. amazonicus, while for the HSI no significant difference (p>0.05) was found between the two fish species. Positive relationship regarding spleen and liver weight to body mass was observed for C. macropomum. However, this relationship was not found for spleen weight to body mass of B. amazonicus, indicating a species-specific pattern. The Kn, SSI and HSI of C. macropomum and B. amazonicus suggest that both species presented good health condition. Therefore, it is recommended the use of these indices as indicators of the health condition for other fish species that have not been studied.