This study assesses the respiratory dynamics related to stress parameters and resting time before slaughter, in the quality of surubim (Pseudopatystoma spp.) fillets. A completely randomized design was conducted using five treatments: resting time before slaughter of 0, 2, 4, 8 and 24 hours, with 15 fish sampled per treatment. Time 0 corresponded to the treatment without resting time, where the fish were slaughtered immediately after arriving at the processing plant. The resting time did not affect the electrolyte balance, hemoglobin, plasma, hepatic glycogen, myofibrillar fragmentation index (MFI) and water holding capacity (WHC) of surubins. However, with increased resting time, there was a significant decrease in muscle glycogen and an increase in blood pH and blood bicarbonate levels. Additionally, respiratory parameters showed an increase in pO₂ and, consequently, in O₂ saturation and a decrease in pCO₂.The hematocrit and MCV values of the surubins after 24 hours of resting decreased significantly. In the first hours of resting, the highest values of erythrocytes and CHCM were observed. The lowest level of stress was observed for fish having 24 hours of resting. Fish having longer resting periods (8 and 24 hours) presented fillets with a higher pH (P <0.05) and the rigor mortis establishment time was shorter for the first 2 hours and 24 hours of resting time. There was a linear decrease in fillet lightness and an increase in the intensity of red (CIE a*) color up to 24 hours when resting was increased. In CIE b*, a linear decrease (P <0.05) of the yellow intensity of the fillets was observed as the surubim resting time increased. A resting time of 4 to 8 hours before slaughter is effective in reestablishing homeostasis after transporting surubim, providing fillets with higher quality and a greater length of the pre-rigor mortis period.

Foram avaliados tempo de indução, tempo de recuperação e respostas fisiológicas de cacharas Pseudoplatystoma reticulatum submetidos ao eugenol e mentol. Foram utilizados 42 indivíduos com peso total médio de 205,5 ± 59,13 g e comprimento total médio de 33,5 ± 2,36 cm, dos quais um grupo foi exposto ao eugenol 100 mg L-1 (n=14), outro grupo ao mentol 150 mg L-1 (n=14) e um grupo controle (n=14), não exposto a nenhum anestésico. No momento 0 e 24 h após indução foram realizadas colheitas sanguíneas nos peixes de cada tratamento (n=7) para avaliação dos parâmetros hematológicos e glicose plasmática. Os resultados foram submetidos à análise de variância (P<0,05) e as médias quando significativas foram comparadas pelo teste de Tukey (P<0,05). Ambos os anestésicos em suas respectivas concentrações induziram os peixes à anestesia cirúrgica. O tempo de recuperação dos animais apresentou redução significativa (P<0,05) quando expostos ao mentol 150 mg L-1. Houve efeito de interação entre os fatores para o parâmetro hematológico VCM, visto que os peixes anestesiados com eugenol apresentaram redução significativa (P<0,05) do mesmo 24 h após anestesia. Os valores de glicose plasmática não diferiram entre si 0 h após indução, sendo que 24 h depois, tanto os peixes do grupo controle quanto os expostos ao eugenol e mentol apresentaram redução significativa (P<0,01) dos níveis plasmáticos. O eugenol a 100 mg L-1 e o mentol a 150 mg L-1 podem ser utilizados seguramente na indução anestésica de cacharas durante a realização de biometrias.

Selection can affect growth, changing performance and asymptotic values. However, there is little information about the growth of families in fish breeding programs. The aim of this study was to evaluate the performance and growth of families of Nile tilapia AquaAmérica. Twenty AquaAmérica families cultivated in a net cage (13.5 m3) for 181 days were evaluated. The nonlinear Gompertz regression model was fitted to the data by the weighted least squares method, taking the inverse of the variance of weight in different families and at different ages as the weighting variable. The model was adjusted to describe the growth in weight and morphometric characteristics. Two families showed highest (P<0.05) weights at both 133 days (family AA10: 743.2 g; family AA16: 741.2 g) and 181 days (family AA10: 1,422.1 g; family AA16: 1,393.4 g) of the experiment. In both experimental periods, the males showed a heavier weight, with the greatest contrast between the sexes occurring at 181 days. The analysis of the three most contrasting families (AA1, AA9 and AA14) showed that the asymptotic value for weight was higher (P<0.05) in family AA9 (3,926.3 g) than in family AA14 (3,251.6 g), but specific growth rate and age at the inflection point did not differ significantly between families. In conclusion, two of the 20 families were superior; males exhibited a greater growth, mainly in the period of 181 days; and the growth curve differed between the families, especially for asymptotic weight.

The objective of this study was to evaluate the effects of three levels of lipids in the diet on growth, metabolism, and intestinal and hepatic histopathology in discus fish (Symphysodon aequifasciatus). Fish were stocked in quadruplicate in aquarium (50L) and were fed experimental diets containing three levels (3%, 10%, and 14%) of dietary lipids (LP). At the end of the trial, no significant differences in growth performance were observed. Fish fed diets with 3% and 10% LP exhibited significantly higher protein efficiency rates compared to those fed the 14% LP diet. A significant increase in lipase and alkaline phosphatase activity was observed in fish fed 14% LP diets. The inclusion of 14% lipids in the diet led to a decrease in albumin activity and an increase in the height of the intestinal villi. Although no significant differences were observed in aspartate aminotransferase, alanine aminotransferase activities, and size of hepatocytes. The histopathology of the liver indicated reduced hepatocyte size, lipid vacuoles, and sinusoidal space in the group fed the 3% LP diet. In conclusion, the use of 10% LP diet was found to be more favorable for liver health and growth performance.

Hybrid cachapinta (Pseudoplatystoma reticulatum × Pseudoplatystoma corruscans) has been a very popular fish and is well accepted by consumers internationally, however, there is a lack of information showing its advantages relative to its parental cachara (P. reticulatum) species. This study was undertaken to compare the processing yield and meat quality characteristics of cachara and the cachapinta hybrid raised in net cages. Cachara’s weight was 1.51 ± 0.27 kg and total length was 49.85 ± 6.22 cm at harvest and was not significantly different from hybrid cachapinta that weighed 1.50 ± 0.11 kg and measured 50.83 ± 3.91 cm. Additionally, the two groups were not statistically different on gutted fish dress out (cachara: 89.97 ± 1.28%; cachapinta: 90.23 ± 0.30%) and other processing yield parameters. Skinless shank fillets with an average weight of 503.77 ± 0.10 g (cachara) and 514.41 ± 0.04 g, (hybrid cachapinta) were evaluated for pH, water holding capacity, colour (L*, a*, b*), shear force and lipid oxidation (TBARS). There were no differences in the fillet meat quality between cachara and hybrid cachapinta tested in this study. In conclusion, both genetic groups had similar processing yield and fillet meat quality characteristics when produced in net cages.