With the intensification of fish farming, the amount of residues also increased. One of the by-products generated is leather. However, several factors influence its quality, among them, the types of tanning used. Paiche (Arapaima gigas) is the largest freshwater fish in the world, and therefore has great potential in the use of leather, in addition to being one of the most cultivated fish in the Rondônia state. The aimed was to evaluate the physicomechanical resistance, histological and morphological aspects in different directions of the fibers of the paiche to evaluate the tanning with chromium oxide and vegetable tannin. Paiches with an average weight of 12.0 kg were used, skins were made and tanned using chromium and vegetable tannin as techniques. After tanning, 20 specimens were removed in longitudinal, transverse and diagonal directions to the fish body, to determine resistance in dynamometer and leather for histological analysis, scanning electron microscopy and physical-chemical analysis. The average thickness of the specimens of the leathers ranged 1.79mm to 2.82mm, in addition, there was no interaction between the type of tanning agent and the directions obtained for strength, traction and elongation. Regarding the progressive tearing test, there was also no interaction effect. However, the defined factors had relevant differences for the maximum and average amount applied, and the leathers tanned with vegetable tannin expanded to larger dimensions 110.19 and 85.52 N. According to the images obtained by histology and scanning microscopy, they presented that in the longitudinal and transverse direction the collagen fibers are presented in layers parallel to the leather surface and in the diagonal direction the interlacing is more intense, that is, in addition to the overlapping layers intercalated thinner, close to the surface, fiber bundles can also be seen crossing each other. It is concluded that leathers tanned with vegetable tannin have less resistance than leathers tanned with chromium salts for traction to rupture and greater resistance to tear.

The aimed of the study was to evaluate the caloric value as a function of the proximal composition and correlate the selling price with the nutritional values ​​of commercial cuts of tambaqui (Colossoma macropomum) and pirarucu (Arapaima gigas) in different weight classes. The sample collections were performed in two processing units located in the state of Rondônia, Brazil. Were 200 tambaquis in five weight classes were studied. And, were 77 pirarucus were studied in seven weight classes. The design was completely randomized, with processing carried out in triplicate. The Kruskal-Wallis test (α=0.05) was used to compare the averages and the Spearman correlation (ρ) between price and nutrients. The commercial cuts with the highest caloric value were the tambaqui filet (145.70 kcal/100g) and the pirarucu filet mignon (119.11 kcal/100g) (p<0.05). And the less caloric commercial cuts were steak of tambaqui (100.47 kcal/100g) and pirarucu loin 102.01 kcal/100g) (p<0.05). It was also observed that the variables caloric value and protein content did not correlate with the price of the kilo of fish for the different commercial cuts, which leads to infer that, possibly, the sensorial, market and cultural factors were responsible for the price variations. Regarding the caloric value according to the composition of the tambaqui, the Class 4 was the most efficient category for production and commercialization. And in the composition of the pirarucu, the Class 4 presented satisfactory values of proteins and lipids and a good percentage of mineral matter.

The aimed of this study was to evaluate the mineral composition in commercial cuts of tambaqui (Colossoma macropomum) and pirarucu (Arapaima gigas). Were compared to the minimum values of daily consumption of minerals recommended by the World Health Organization (WHO). The experimental design was completely randomized, with processing performed in triplicate. Data were submitted to ANOVA. If ANOVA appeared statistically significant (α=0.05), the means were compared by Tukey’s Test. There was a difference (p<0.05) between commercial cuts of the tambaqui for different minerals. Tambaqui ribs and band presented the highest values of total iron 1.08 ± 0.12 mg/100g compared to other commercial cuts. The mineral elements Na+, K+, Ca2+ and Mg2+ expressed the highest values for the tambaqui steak, 301.00 ± 80.58, 457.00 ± 129.33, 36.00 ± 4.36 and 46.90 ± 4.68 mg/100g, respectively. There was a difference (p<0.05) between commercial cuts of the pirarucu for different minerals. The mineral elements Total Iron, Na+, K+ and Ca2+ expressed the highest values for pirarucu loin, 0.80 ± 0.07, 406.00 ± 117.50, 529.30 ± 130.58 and 32.00 ± 5.12 mg/100g, respectively. However, Mg2+ expressed a higher value for pirarucu tail fillet 37.10 ± 4.99 mg/100g. The tambaqui steak and pirarucu loin were the cuts that best met the minimum needs for mineral supply.

O estudo teve como objetivo analisar a viabilidade econômica de uma piscicultura localizada no município de Urupá-RO, por meio dos indicadores econômicos, com ênfase no período de retorno de capital (Payback), valor presente líquido (VPL) e taxa interna de retorno (TIR). Os custos com ração para engorda representaram 81,06%. O empreendimento obteve Payback de cinco anos e seis meses, e uma média de índice de lucratividade de 46,18%. No entanto, a taxa interna de retorno (TIR) expressou-se acima da taxa mínima de atratividade chegando ao sexto ano com 17,0% e VPL positivo para o sexto ano de cultivo de R$ 21.098,41. As projeções realizadas demonstram viabilidade operacional ao longo do tempo. Portanto, a piscicultura possui viabilidade econômica para investimento, porque o valor empregado na atividade é recuperado, com potencial de gerar excedente e se manter exequível ao longo do tempo.

This study aimed to compare the resistance of the Oryctolagus cuniculus L. (rabbit) and Oreochromis niloticus L. (Nile tilapia) skins, as well as to observe the design of the flower of these skins and the morphology of the dermis. Tilapia and rabbit skins were placed inside the same equipment (tannery machine) for the chromium salt tanning process. The flower design of the fish leather distinguishes it from the rabbit leather, the latter being constituted by the opening of the hair follicles and pores, while the fish leather is constituted by the presence of protective lamellae and insertion of the scales. The dermis of rabbit skin consists of thick bundles of collagen fibers arranged in all directions, which differs from the morphology observed in the dermis of fish skin. However, in the Nile tilapia skin dermis, overlapping and parallel layers of longitudinal collagen fiber bundles are observed, these layers are interspersed with fiber bundles crossing the sking surface (transversely), tying the fibers together and providing greater strength, which can be proven by the strength test. The fish leathers, despite having less thickness (1.0 mm), demonstrated significantly greater tensile strength (13.52 ± 1.86 N mm−2) and tear strength (53.85 ± 6.66 N mm−2) than rabbit leathers, that is, (8.98 ± 2.67 N mm−2) and (24.25 ± 4.34 N mm−2). However, rabbit leather demonstrated higher elasticity (109.97 ± 13.52%) compared to Nile tilapia leather (78.97 ± 8.40%). It can be concluded that although the rabbit leather is thicker due to the histological architecture of the dermis (thick bundles of collagen fibers arranged in all directions with no pattern of organization of collagen fibers), it shows less resistance than Nile tilapia leather, which demonstrates an organization of overlapping and parallel layers and intercalating collagen fiber bundles transversally to the surface, functioning as tendons for the swimming process. It is recommended to use a piece of fabric (lining) together with the fleshy side of the rabbit leather, to increase resistance when used in clothing and footwear, as these products require greater tensile strength. Thus, it minimizes this restriction for the use of rabbit leather in the aforementioned purposes.