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Tambaqui, a species native to the Amazon and Orinoco Basins and their tributaries, has a history marked by biological resilience that makes this species a model for studies focused on ecology, physiology, and fish farming. In addition, it is of economic interest, due to its favorable characteristics for production in farms and its unique flavor. As the tambaqui responds in a unique way to several environmental disturbances of natural origin, the species is often used in environmental studies. Some of these studies have been revisited in this review. We revised aspects related to its natural history, habitats and geographic distribution, physiological and biochemical adaptations, and zootechnical performance. The extraordinary adaptation of the tambaqui is the fast expansion of its lower lip when exposed to low oxygen availability that is improved simultaneously with other adjustments. The resilience of this species to significant alterations in water pH is also surprising, and is incomparable with that of other species, as only when it is exposed to pH 3.5, does the tambaqui begin to present physiological-biochemical disturbances. The analysis of the gene expression of tambaqui specimens under different experimental conditions has shed light on the adaptive mechanisms used by this unique Amazonian species. In this sense, this review sought to gather information regarding the tambaqui, and its many biological features employed to survive environmental challenges.

While in all vertebrates, growth hormone (GH) promotes post-natal growth, in fishes it also affects such metabolic functions as foraging rate, digestion, osmoregulation, and reproduction. The promoter region of the GH gene is an important target for studies of mechanisms regulating its expression, and polymorphisms within the promoter have been associated with performance traits in fishes. We used Thermal Asymmetric Interlaced PCR (TAIL-PCR) to amplify and sequence the 5′-flanking regions of the Colossoma macropomum GH (cmGH) gene. Based on a sequence of 1,038 bp, we designed three specific nested primers (R-290, R-186 and R-26) which were used with shorter arbitrary degenerate primers to amplify the 5′ proximal region of the cmGH gene. We identified a tetranucleotide (ATCC)4 microsatellite motif in this region, exhibiting four alleles (118, 122, 126 and 130 bp) within the population study. Genotypes at this locus deviated significantly from Hardy–Weinberg expectations (p ≤.05) and showed a low level of polymorphism (polymorphic information content = 0.163). High homozygosity (FIS = 0.147) was observed in the overall population. The polymorphism at the microsatellite makes it an important candidate for association studies between the respective genotypes, growth rate and other traits in farmed populations. Such studies may contribute to future breeding programs using marker-assisted selection upon this aquaculturally important species. Accepted version

Tambaqui, Colossoma macropomum, were fed with three vitamin C levels and two iron levels for 21 d: Diet 1 without vitamin C and with 30 mg of iron/kg; Diet 2 with 100 mg of vitamin C and 30 mg of iron/kg; and Diet 3 with 100 mg of vitamin C and 300 mg of iron/kg. Mortality was not observed during the feeding experiment. There were no changes in hematological parameters in fish that were fed the different diets. Iron contents in liver, muscle, and plasma were significantly different in fish fed with different iron content in the diets; when associated with vitamin C, changes were observed only for plasma iron. Therefore, tambaqui exhibits varied iron absorption in response to different levels of iron with and without vitamin C, a conclusion consistent with findings for other species of fish.