Abstract: Growth of the early juvenile Tachypleus tridentatus was studied. At room temperature, T. tridentatus were artificially bred and cultivated from 2014 till 2016.The growth indices, including wet body weight, prosomal length and width, opisthosoma length and width as well as telson and whole lengths, of the fish were measured to establish power function models for the T. tridentatus of 1^st to 5^th instar age by regression analysis. The converted logarithmic growth indices were used to obtain linear regression equations, which showed a correlation coefficient, R², for all except that of opisthosoma length vs. prosomal width, was greater than 0.900 at P<0.01. The wet body weight and telson and whole lengths were positively allometric with the prosomal width; while the opisthosoma width, isometric with the prosomal width; and, the prosomal and opisthosoma lengths, negatively allometric with the prosomal width. Subsequently, separately measured data on T. tridentatus of 1^st to 5^th instar age as well as those of 6^th instar age were entered the equations for validation. The results indicated all models fitted well with data and were highly extrapolatable.

Key words: Tachypleus tridentatus, allometric growth, regression analysis