Salt-water recirculation systems using automatic feeders are a new frontier for marine aquaculture. The definition of the feed frequency is fundamental for the correct use of automatic feeders. Different feeding frequencies (1, 3, 6, 12 and 18 times a day) using automatic feeders were evaluated in two experiments on the performance of the dusky grouper (Epinephelus marginatus) in salt-water recirculation system. In the first experiment, three feeding frequencies were evaluated: feeding once a day; three times a day and six times a day. In the second experiment, three feeding frequencies were evaluated: feeding six times a day; 12 times a day and 18 times a day.Waters parameters (temperature, salinity, oxygen level, total ammonia, pH and oxidation-reduction potential) were maintained at specific ranges for the species. Among all the evaluated frequencies, 12 times a day provided the best productive performance, obtaining superior results for final weight, final biomass, specific growth rate and daily weight gain. For juveniles of the dusky grouper, the ideal feeding frequency is regular feedings every 2 hours, which is impractical to run without the use of automatic feeders.

Anesthesia can be utilized as a non-lethal procedure to allow easy handling of teleosts and elasmobranchs in captivity or in the wild. For this, anesthetic protocols need to be established according to the species. The aim of this study was to determine the ideal concentration of eugenol for anesthesia of Zapteryx brevirostris. Four concentrations were tested: 21.25, 42.50, 85.00 and 170.00 mg L-1 (ratio of 1:5 with absolute ethanol). The perfect concentration of eugenol for this species was 85.0 mg L-1 , which enabled up to 300 seconds of work on the fish, without any response to handling.

Environmental enrichment can be an important tool to improve the productive performance of dusky grouper Epinephelus marginatus (Lowe, 1834). The goal of this study was to evaluate the preference for shelters and the effect of the availability of shelters on the productive performance of dusky groupers juveniles in salt water recirculation system. Two trials were conducted, the first one to determine the preference for different types of shelters (rocks, bricks and PVC pipes of different colors) and the second one on the use of shelters, with three treatments (T1 = without shelter; T2 = one shelter per fish and T3 = two shelters per fish). The dusky grouper showed preference for shelters of PVC tubes of brown color. The use of shelters favored better productive performance of the species in salt water recirculation systems.