Weight and morphometric growth of Pacu (Piaractus mesopotamicus), Tambaqui (Colossoma macropumum) and their hybrids from spring to winter

Peso e crescimento morfométrico de pacu (Piaractus mesopotamicus), tambaqui (Colossoma macropumum) e seus híbridos da primavera ao inverno

ABSTRACT:

This study aimed to evaluate weight and morphometric growth of the products of the complete diallel cross-breeding between pacu and tambaqui during the period from the end of spring to the beginning of winter. Was used 400 pacu, tambaqui, tambacu and paqui. 20 fish from each group were collected, weighed and submitted to morphometric evaluation every 28 days. The Logistic function adjusted better to describe the growth in body weight and the morphometric measures for age on all the genetic groups. The studied groups presented similar behavior of growth for body weight and morphometric measures. There were significant differences between the genetic groups regarding parameters A (asymptotic value) and B (integration constant) for body weight and for all the morphometric measures evaluated. For the parameter K (maturity rate), there were significant difference between groups for body weight, head length and body height. The groups possibly were affected the decrease of temperature. The Tambacu was superior to the Paqui in all the variables evaluated for the parameter A, and was also superior to the pure breed, except for head length and body width.

INDEX TERMS:
Pacu; Piaractus mesopotamicus; tambaqui; Colossoma macropumum; growth curve; cross-breeding; body form; fishes; poikilotherm animals