This paper reports the triiodothyronine's (T3) effects on the early growth and survival of piracanjuba (Brycon orbignyanus) produced from fertilized eggs hormone exposed. The study was carried out in two phases. In the first phase, eggs divided in 6 batches were immersed in T3 solutions: 0.01; 0.05; 0.1; 0.5 ppm; 1 ppm and control (no T3). After a 15-min immersion, eggs were transferred to incubators where larvae were kept up to 72 h after hatching. Larval weight, length and yolk sac volume were determined every 12 h. Sixty and 72 h after hatching, larvae exposed to 0.5 ppm T3 were significantly heavier than the others, and those exposed to 1 ppm T3 showed the lowest weight. The yolk sac absorption was not affected. In the second experimental phase, the resulting fry from the first phase were stocked into 3 boxes per treatment (5 larvae L(-1)) and fed with plankton, fish larvae and feed prepared in the hatchery (48% CP) in the first 3 days, plankton and feed from the 4th to the 10th day and only feed in the next (last) 5 days. Fry weight, length and specific growth rate were determined at 1, 5, 10 and 15 days. Survival was calculated in the last day. In the 15th day, fry length did not differ among treatments but the weight of the control group was higher. Higher survival in the T3-treated groups suggested lower predation among fry. The results allowed us to conclude that there was no expressive effect of T3 on the growth, but it improved the survival of the piracanjuba progeny.
The arowanas, fishes of Gondwanan origin, are represented in South America by the genus Osteoglossum. All species were initially reported as being exclusive to the Amazon region, with O. ferreirai restricted to the Negro River basin and O. bicirrhosum to the Amazon and Essequibo Rivers basin. Starting in the mid 1970's it was reported that O. ferreirai also occurs in the Orinoco River basin. In all regions the arowanas assumed significant socio-economic importance due to their popularity in the international ornamental fish trade, leading to over-exploitation of both species in some areas. The Orinoco populations are particularly heavily exploited, and thus conservation and management measures are needed. Both depend on the clarification of taxonomic status, and phylogenetic distinctness of the Orinoco populations. With the goal of molecularly characterizing the two species of Osteoglossum, and comparing populations of Osteoglossum from the Orinoco and Amazon basins, we characterized individuals sampled from eight localities, one in the Orinoco River basin and seven in the Amazon River basin. We sampled 39 individuals, obtaining 1004 base pairs, of which 79 were synapomorphies. Genetic distance between the two species calculated using the HKY + G model of molecular evolution was 8.94%. Intraspecific distances ranged from 0.42% in O. bicirrhosum to 0.10% in O. ferreirai. The genetic characterization confirmed the taxonomic status of O. ferreirai in the Orinoco basin, and suggested that its distribution in the Orinoco basin is unlikely to be the result of vicariance or natural dispersal, but rather an anthropic introduction.
The effect of food restriction and refeeding on some physiological variables in yamú (Brycon amazonicus) was evaluated using 1115 juveniles (initial weight 217.75 g ± 14.74 g), distributed in three ponds. The groups were randomly assigned one of the following treatments: 1) Control (C), fed every day; 2) Moderate restriction (MR), restriction during two days and refeeding during three; and 3) Severe restriction (SR), total restriction during five weeks and refeeding from week 6 to 12. Blood samples from 7 animals from each treatment were taken on days 1, 35, 42, 56, 70, and 84 to determine hematocrit, proteins, glucose, lactate, triglycerides, cholesterol, cortisol, T3, and insulin. The animals were sacrificed and their livers removed to calculate the hepatic glycogen. The experimental design used was a fixed effects mixed model of 3 treatments and 6 samples, with sampling nesting in the treatments. A variance analysis was performed to analyze the data; the Tukey-Kramer test a variance analysis was used in the cases with significant differences. No significant differences (p˃ 0.05) were found for hematocrit, protein, glucose, cortisol, and lactate. The insulin and T3 showed differences among treatments on day 35, but not on day 84, the same as cholesterol and hepatic glycogen. Triglycerides showed differences throughout the study, SR showed the lowest levels on day 84. The results allow us to conclude that, despite the partial feed restriction, there were no adverse effects on the metabolism of Brycon amazonicus.
La creación de ACCUA se fundamentó en las consideraciones del informe titulado Aquaculture in Colombia (Pardo-Carrasco et al., 2018), presentado en LAQUA18, el cual pondera la producción acuícola de especies exóticas y nativas mediante tecnologías amigables con el medio ambiente en diferentes regiones del país. En Colombia el aporte de la acuicultura a la producción pesquera nacional supera el 27 % de la producción total, siendo estos los productos de la acuicultura más importantes, en su orden: la Tilapia (95 % Tilapia roja: Oreochromis sp.), las Cachamas (Piaractus brachipomus y Colossoma macropomun), los camarones de cultivo (Litopenaeus vannamei y L. stylirostris) y la Trucha (Oncorhynchus mykiss).
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