The purpose of this paper was evaluate the palatability of the meat of tambaqui of different ages and environments, both from natural and cultivated systems. In order to carry out the consumers' acceptability test concerning the tambaqui meat from different feeding, 14 wild fish and 14 cultivated ones were used, with average weight ranging from 0.8 to 8.5 kg, already killed, cut and fresh. The samples were separated according to the environment (wild and cultivated), stored in thermal box and processed as standard fried ribs. The total of 200 untrained tasters of both genders was consulted, with the intention of finding the common public's opinion. The evaluated items were: flavor, color, smell and texture. The samples from pisciculture obtained better acceptability results regarding young fish's meat (63.5%), and the adult's (78.0%), as compared to the same age groups for the natural environment fish with 49.7% and 61.0% of the total evaluated, respectively. Thus, the sensorial analysis demonstrated a greater preference for cultivated tambaqui's meat, with emphasis on the items flavor and texture, which can be attributed to feeding quality (fish food with 28% of crude protein) and husbandry employed in the farming system

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The genus Cichla is a highly diverse group, with 16 species already described. Externally, some species are very similar and discriminating between them may be very difficult. Nevertheless, discrimination of fish stocks is essential for management purposes. Morphometric analyses of otoliths have been successfully used to distinguish species and fish stocks, especially in marine environments. This study evaluated whether sagittal otolith shape can be used to discriminate among the species Cichla temensis, C. monoculus, and C. orinocensis, as well as within populations of C. temensis in rivers of the Amazon. Shape indices and Fourier coefficients were used to describe the shape of the otoliths. Among the groups of species, the morphology of the sagittal otolith of C. temensis was totally distinct from the species C. monoculus and C. orinocensis. While among populations of C. temensis, individuals from the Negro and Jatapú Rivers were different, regardless of the methods used. These results confirm the ability to differentiate species and populations by using the morphology of otoliths. However, more research is needed to verify the role of genetic versus environmental and biotic effects, and thus be able to explain the discrimination observed in otoliths.

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Much has been written about the negative impacts of large hydroelectric dams on fish species diversity in the Amazon River Basin; however, less is known about the impacts of small dams in streams that are created for fish aquaculture. Our study of fish assemblages upstream and downstream of fish farm dams in Rondônia State, Brazil, revealed that the dams act as physical barriers to fish movement and that upstream assemblages showed lower measures of diversity and abundance compared to downstream. The greatest impact was the obstruction of upstream movement of a number of fish groups, coupled with isolation and disappearance of relatively rare fish species living upstream. The fish species most affected were from frugivore, herbivore and detritivore trophic levels that are associated with migration and the forming of schools (potamodromous species), although the impact was also evident in piscivorous fish commonly found in lentic habitats. Although stream dams may cause small negative effects relative to huge hydroelectric barriers, the cumulative impact of hundreds of fish farms in stream channels could be considerable. Amelioration of the damage caused by fish farm impoundments will require (1) design of effective fish passage systems around dams to reduce impact on fish diversity and (2) prohibition of the complete stream blocking to build these fish farms, which will require derivative channels to their water supply.