Growth patterns of male and female of Nile tilapia (Oreochromis niloticus) GIFT variety

The aim of this work was to estimate the growth pattern of GIFT tilapia using nonlinear model Gompertz and verifying the differences between growth pattern of males and females. The Gompertz model has been tested within eight variations. The first model had not restriction on the parametric space, but the other models presented several numbers of restrictions, ranged from 1 to 3 restrictions. Were estimated the growth pattern for body weight, total length, body height, body width and head size. Model three was the fittest for total length, weight, body width, and size of the head, while for height of the body the model one has the better fit than the other models. Comparing the weight increment with the other characteristics, it was observed that the inflection points of the morphometric characteristics ranged from 121.2 to 156.2 day for females and 134.1 to 166.6 day for males, while that for weight the inflection point was 340.4 and 322.9 day to males and females respectively, showing that the form of the fish was determined in smaller age than weight. The growth pattern of the body shares constituents and weight of males and females GIFT differ, confirming sexual dimorphism. Males and females presented equal growth relative in the inflection point for the characteristics majority of evaluated, except for body height.