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.

Mercury is an element with potential risk to fish and those who consume it. Thus, this study aimed to determine the levels of total mercury (THg), carry out a health risk assessment related to the consumption of the freshwater stingrays Potamotrygon motoro, and determine the physical and chemical properties of the water where stingrays occur. Stingrays of the species P. motoro were obtained from the Amazon River, and samples of the animals’ musculature were collected to determine THg levels. Risk assessment was conducted using pre-established formulas of estimated monthly intake (EMI), maximum monthly intake rate (IRmm), and hazard quotient (HQ). Three population scenarios were evaluated, considering both sexes and differences between rural and urban areas. There was no relationship between weight and THg concentration nor between total length and THg concentration. Higher EMI values were observed in rural children; for the IRmm, male children had the lowest consumption levels. For the hazard quotient, there was a similarity between the three age groups when comparing the male and female sexes. In addition, the representatives of the rural area always had lower values than the urban area. Freshwater stingrays, like other elasmobranchs, can be crucial animal species because they act as sentinels in studies that assess harmful chemicals like mercury.

The objective of this study was to characterize and compare the hematological variables (erythrogram, thrombogram, leukogram and plasma metabolites) of three cichlid species: Cichla monoculus, Cichla temensis and Cichla vazzoleri. A total of 45 specimens were captured in Balbina lake, Presidente Figueiredo, Amazonas, Brazil, with the aid of a rod and reel or hand line, with natural or artificial bait: 15 C. monoculus, 15 C. temensis and 15 C. vazzoleri. Their blood was removed by means of caudal puncture of the dorsal aorta, and hematological data were determined in accordance with methodology previously described in the literature. The erythrogram showed similarities between the species, while the thrombogram showed differences between C. vazzoleri and the other species studied (C. monoculus and C. temensis). The total leukocyte counts for C. temensis and C. vazzoleri were higher than those of C. monoculus. The predominant leukocyte in C. temensis and C. vazzoleri was lymphocytes, whereas it was monocytes in C. monoculus. The plasma metabolites showed differences between the three cichlid species, regarding their glucose, cholesterol, urea and potassium levels. It is concluded that these three species present hematological differentiation, thus indicating that they have differentiated blood-cell immune responses and plasma metabolite physiology.

Lysine effect on the characterization of fillet, by-products, residues, and morphometry of tambaqui Colossoma macropomum (Cuvier, 1818)

A Etnociência surge como uma importante ferramenta integradora do conhecimento acadêmico e do conhecimento dos pescadores. O objetivo do presente estudo é realizar uma análise do perfil socioeconômico e do conhecimento tradicional sobre as arraias de água doce em relatos de pescadores no município de Barcelos, Amazonas. Foram entrevistados 54 pescadores que foram afetados por acidentes com arraias. Observou-se que 89,0% são do sexo masculino, demonstrando a manutenção das atividades de pesca que são passadas pelas famílias de crianças e jovens. A proporção de casos ocorreu com pescador com mais de 50 anos (62,2%). Há uma predominância do uso de puçá e rapiché que é um tipo de pesca ativa na qual não causa nenhum dano aos animais. Um total de 2,0% não identificou as cinco espécies presentes no rio Negro. Entre os sintomas apontados pelos pescadores após o acidente, foram citados dor, edema e, algumas vezes, necrose. É possível auxiliar os pescadores de águas doce sobre como se sucedeu os acidentes, as localidades e os mecanimos de atuação dos venenos, bem como a forma com que os pescadores utilizaram para minimizar os efeitos dos ferimentos. As informações geradas aqui podem servir de base para que os ribeirinhos ao ser acidentados por arraias de água doce tenham uma forma de mitigar ou até mesmo de eliminar a dor causada pelo veneno presente nos ferrões desses animais tão temido pelos povos ribeirinhos da Amazônia.