Effect of stocking density and vertical substrate addition on growth performance and health status of fat snook Centropomus parallelus

• Higher stocking density (350 e 500 fish m− 3) in C. parallelus culture did not affect the zootechnical performance.
• Vertical substrate seems to improve the hematological and parasitological conditions of fat snook C. parallelus.
• Hematological and parasitological analyses used as a tool to corroborate the fish performance in snook culture.

Fat snook Centropomus parallelus is one of marine finfish species with farm potential in Brazil, although some adjustments in farm practices are required to optimize its production. The aim of this study was to evaluate the effect of different stocking densities and vertical substrate addition on growth, survival and health status, such as hematological and parasitological aspects, in fat snook C. parallelus culture. The experiment was carried out evaluating 200, 350 and 500 fish m− 3 with (S) or without vertical substrate, totalizing 6 treatments as follows: 200-S, 200, 350-S, 350, 500-S and 500. Eighteen experimental units (20 L plastic bins) were settled-up in a recirculation aquaculture system. After 51 days, the results showed that the highest stocking densities (350 and 500) did not affect the final weight (~ 29 g) and survival (100%). Moreover, zootechnical performance was not influenced by the vertical substrate addition. Fish presented 100% prevalence of monogenean in all treatments, with a significant increase (p < 0.05) in the mean intensity in those kept at 500 fish·m− 3. The fish of this density had higher (p < 0.05) RBC count and thrombocyte number when compared to other treatments. On the other hand, after hematological and parasitological analysis, the use of 350 fish·m− 3 with (S) substrate addition is recommended aiming a better health condition of C. parallelus in a recirculation aquaculture system.Statement of relevanceThis statement is mainly due to its application (vertical substrate) in commercial farms and its benefits observed in hematological and parasitological conditions of fish.