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.

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The registration of reproductive processes of elasmobranchs is rare and little documented in public aquariums. The present work registers the first case of dystocia in cownose ray (Rhinoptera bonasus), (Mitchill, 1815). The ray maintained in captivity by 16 years, it presented a gestation of 14 months. There was not occurrence of the natural childbirth, being necessary the human intervention through obstetric maneuvers for the retreat of the fetus. The described procedures can be used as reference in other cases of dystocia with the species.

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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.

Due to the decline of fishing stocks, aquaculture has been expanding throughout the world. Taking into account the possibility of conflicts of aquacultural activities in areas of environmental protection, this study aims at assessing the effects of mariculture upon the local ichthyofauna of Itaguá Bay in Ubatuba, São Paulo state, Brazil, which is within a marine protection area. In order to do so, the fish community was analyzed in areas with mussels and macroalgae farms and in areas without any maricultural activities. After six months of sampling efforts, 230 individuals were captured from 19 different species and 15 families. There was no difference in catchability, richness, diversity, and evenness among the areas. Nevertheless, the species composition was distinct in areas where mussels were farmed. These areas have presented twice as much fish biomass than the others. Based on these results, we can observe that the environmental alterations caused by mussel farming, are sources of habitat complexity, hence able to enrich the marine fauna of the region. Thus, we conclude that mariculture, specifically mussel farming, has a positive impact on ichthyofauna, contributing to biodiversity maintenance in protected areas.

The objective of this work was to evaluate the growth performance of common snook (Centropomus undecimalis) subjected to different feeding rates and frequencies using automatic feeders. Two experiments of 60 days each were carried out. In the first one, 20 fishes per tank were distributed in three feeding rates of: 5, 10, and 15% body weight per day. In the second experiment, 20 fishes per tank were distributed in nine tanks, in three feeding frequency: once a day, three times a day, and six times a day. Water parameters were maintained at the recommended level for the species. Final weight, body weight gain, specific growth rate, and feed conversion rate did not differ significantly between the 10 and 15% feeding rates. However, both rates differed from the 5% one. The feeding frequency of six times a day resulted in better values for final weight, final biomass, body weight gain, and specific growth rate. Therefore, common snook fingerlings should be fed at the feeding rate of 10% body weight per day, six times a day, in order to achieve the best growth performance.

Resumo -O objetivo deste trabalho foi avaliar o efeito da privação alimentar e a ocorrência de crescimento compensatório sobre o desempenho produtivo de formas jovens do robalo-flecha (Centropomus undecimalis). O experimento teve duração de 60 dias, em que os peixes -35 indivíduos por tanque -foram divididos nos três seguintes grupos de tratamentos: com alimentação todos os dias (controle); com alimentação cinco dias por semana, seguidos de dois dias de jejum; e com alimentação quatro dias por semana, seguidos de três dias de jejum. Os tratamentos de privação alimentar proporcionaram indicadores de desempenho significativamente inferiores aos do controle. Formas jovens da espécie não devem ser submetidas a períodos de privação alimentar, pelos prejuízos que esta prática acarreta ao desempenho produtivo.Termos para indexação: Centropomus undecimalis, hiperfagia, manejo alimentar, maricultura. Compensatory growth and food deprivation in common snook growth performanceAbstract -The objective of this work was to evaluate the effect of food deprivation and the occurrence of compensatory growth on the performance of common snook fingerlings (Centropomus undecimalis). The experiment lasted for 60 days, when fish -35 individuals per tank -were divided into three groups of treatments, as follows: daily feeding (control); feeding for five days a week, followed by two days of fast; and feeding for four days a week, followed by three days of fast. The treatments of alimentary restriction provided performance indicators significantly inferior to those of the control. Common snook fingerlings should not be subjected to food restriction because of the damages that this practice entails to productive performance.