The common robalo (Centropomus undecimalis) is a species with great importance in national and international markets, due to its high demand and economic value. It is a sequential protondric hermaphrodite species, however, osmotic pressure can affect growth at low salinities affecting the metabolic expenditure of ionic and osmotic regulation and the energy available for growth.
The objective of this study was to evaluate the growth parameters of Common Snook juvenile sea bream caught in the Ciénaga Grande de Santa Marta (Colombian Caribbean) with an average weight of 13.5 cm 2.5, cultivated in a sweetish culture. For the experiment the animals were randomly distributed in tanks of 2000L to a density of 16 fish per tank, where three diets formulated at 45% PB were evaluated (Table 1) as follows: T1: 0% without replacement of fishmeal by soya meal, T2: 35% replacement and T3: 55% replacement), each with three replicates. Each diet was performed a proximal analysis, fed to 5% of biomass and every 20 days biometrics were performed to adjust the food ration, Daily physical-chemical parameters (oxygen, temperature, and pH) were recorded. The experiment determined the increase in weight and the Specific Growth Rate (SGR). The production variables did not meet assumptions of normality and homogeneity of variance, so the non-parametric test of Kruskal Wallis was applied.
The main results indicated that there was no significant statistical difference of the analyzed variables between the treatments evaluated (Figure 1). The increase in weight varied between 9 and 14.5% being greater in T 0%. The SGR was 0.61 for T 0%, 0.52 for T 35% and 0.54 for T 55%. Survival during the 120 days was close to 100%, mortality of only one individual occurred in the W treatment.
In conclusion, the use of high percentages of soy flour (55%) as a replacement for fishmeal for C. undecimalis juvenile diets is feasible, as it does not affect the main growth indicators.