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Pacu (Piaractus mesopotamicus) is a fish with a high production potential in Brazil. However, one limitation is the excessive amount of ether extract in its carcass, an undesirable characteristic for the consumer. One approach to overcome this limitation is to improve carcass quality through zootechnical additives such as caffeine. The aim of this study was to evaluate the effect of supplementing the diet of pacu with caffeine on cut yield, biological indices, and carcass composition. Two hundred pacu with an initial weight of 1,687 g were used. The animals were allocated to 20 aquaculture cages of 1 m³, with 10 animals per cage. A completely randomized design with four treatments and five replicates was used. The treatments evaluated consisted of four inclusion levels of caffeine: T1 = 0.00 g; T2 = 0.16 g; T3 = 0.32 g, and T4 = 0.48 g caffeine.kg-1 of feed. The findings show that caffeine can be recommended as a diet supplement for carcass improvement of pacu, reducing the fat content and increasing the protein content of the carcass. Caffeine up to 0.32 g.kg-1 of feed can be added to the diet of pacu without affecting its performance or cut yield.

Nitrogen compounds, particularly ammonium, nitrite and nitrate, are a major problem in shrimp production systems. These compounds can accumulate in the aquatic environment and reach harmful or even lethal levels. Thus, monitoring the levels of nitrogenous compounds such as ammonia and studying their effects on the animals are essential. One tool used for this purpose is acute toxicity testing based on the evaluation of LC50 values. Furthermore, tools that can help improve the performance of aquatic organisms in culture are needed. The present study aimed to evaluate the effect of salinity on the toxicity of total ammonia to postlarvae of the freshwater prawn Macrobrachium rosenbergii. For this purpose, acute toxicity testing (LC50-96h) was performed using 540 postlarvae with a mean weight of 0.13 g and a mean total length of 2.47 cm, divided into 54 experimental units of two liters each. A completely randomized design in a 3×6 factorial scheme was used, combining three salinities (0, 5, and 10 g.L-1) and six total ammonia concentrations (0, 8, 16, 32, 64, and 128 mg.L-1), with three replicates per combination. The LC50 values for M. rosenbergii postlarvae at 24, 48, 72, and 96 h and their respective confidence intervals (95%) were estimated using the trimmed Spearman-Karber method. The results showed that salinities of 5 or 10 g.L-1 did not reduce the acute toxicity of total ammonia.

This study aimed to describe and characterize the stages of gonadal development of females of Xiphopenaeus kroyeri caught by artisanal fishers in Espírito Santo state, southeastern region of Brazil. All females (n= 1,831) were subjected to macroscopic and microscopic morphological analysis (n= 333) of the ovaries. From the morphology, coloration and degree of turgidity of the fresh ovary, macroscopic analysis determined five stages of gonadal development. The macroscopic analysis showed difficulties in differentiating the immature and spawning stages due to the similarity between the colors of the ovaries, which confirms the need to perform the macroscopic and histological analysis simultaneously for fisheries management studies. Microscopic observations allowed us to analyze the following six stages of cell development: oogonia, previtellogenic oocytes, primary vitellogenic oocytes, secondary vitellogenic oocytes, mature oocytes and atretic oocytes. From this, five stages of gonadal development were defined, i.e., immature, early development, advanced development, mature and spawned. The presence of peripheral bodies was not observed in this species. These results help to clarify and better understand the reproductive and population aspects of the Atlantic Seabob, which are fundamental for the establishment of management and conservation measures of this resource.

The tambaqui (Colossoma macropomum) is a fish of primary importance in South American aquaculture, principally in the Amazon region and has a particularly unique diet in the wild. Oryza spp, or Wild rice as it is commonly known, is native to the floodplains of muddy rivers in the Amazon region. The aim of this study was to analyze the physical performance and the effects of dietary levels of Oryza spp. via the hematological parameters, total food intake, conversion efficiency, growth ratio and swimming performance of this fish. Diets containing 45% Oryza spp. induced the best performance in tambaqui. Diets containing 15% and 30% did not affect these indices, thus indicating that this amount of Oryza can be used as an alternative energy source for this important species within Brazilian aquaculture.

Three experiments were done with different particle sizes of corn feed on its zootechnical performance, passing rate and apparent digestibility of juvenile tambaqui (Colossoma macropomum). In the first, 200 juveniles were used and distributed in 20 tanks (220 L), 10 fish per unit (four replicates). The experimental system used to record passage time was composed of five incubators with 200 L. In the second, 75 juveniles were used per 55 days (three replications). In the third, 75 juveniles were used and distributed in five incubators of 200 L. All experiments were performed randomly. Different linear behavior treatments were observed for apparent digestibility of crude protein; and the smaller particle size (150 μm) had better results digestibility. smaller particle size of the corn had better results, affected the growth performance of tambaqui and the apparent digestibility of crude protein and ether extract. Thus, is recommended that a particle size of 150 μm of corn be used for tambaqui.

The dusky grouper Epinephelus marginatus is predator fish subjected to be impacted due to the contamination of their habitats. A viable source of metal contamination, i.e., copper (Cu), in this species is the ingestion of contaminated food. The objective of this work was to verify the toxic effects of Cu contaminated feed in dusky grouper. A 15 days trial was conducted with three treatments: control, 1 g and 2 g Cu/kg of fish feed. After the trial, the gut was analyzed for Cu concentration and the liver for SOD and GST activity. The Cu concentration in the intestinal tract was significantly greater in fish from contaminated treatments when compared with control. The SOD was significantly lower in contaminated fish, and the GST did not show differences among treatments. Copper showed to be toxic for the species, as evidenced by gut accumulation and suggested by SOD response.

The Negro river basin is considered the largest area of extractive of ornamental fish in Brazil. This area has fundamental importance for the populations from the Amazon. The present study aimed to describe socioeconomic profile of ornamental fishermen known as "piabeiros" in the Municipality of Barcelos, as well as the ornamental fishery, fisheries area, target species, environments, fishing techniques, equipment, capture techniques and main difficulties faced by the current activity. This study was carried out in municipality of Barcelos, through semi - structured interviews, with artisanal ornamental fishermen (N= 89). The main families of ornamental fish caught and traded were: Characidae, Lebiasinidae, Gasteropelecidae, Cichilidae, Anostomidae, Loricaridae, Potamotrygonidae and Gymnotidae. The main catchment areas were igarapés, lakes, flooded fields, beaches, river banks and igapó forest. Rapiché was the most used equipment in the fisheries both by the fishermen of the urban areas (43.81%) and rural (41.89%). Most of the fishermen are associated with the colony of fishermen of Barcelos (Z33). The data showed that the dynamics of ornamental fishing have changed in a short time and directly affected fishermen, in addition to the low age renewal with the participation of younger fishermen, threatening the transmission of ecological knowledge to future generations. As a result, the increase of the problems related to the productive chain and absence of public power to the activity, since ornamental fishing has already been treated as one of the main economic activities more important for the local communities and for the State of Amazonas.