A review of the species of freshwater prawns belonging to the genus Macrobrachium in Colombia is presented. According to the study, the genus Macrobrachium comprises 20 species for Colombia. The species Macrobrachium cortezi Rodríguez, 1982, M. ferreirai Kensley & Walker, 1982 and M. reyesi Pereira, 1986 are recorded for the first time in the country. Geographical species distributions are updated with basis on new material. Diagnoses, illustrations and a key for Colombian Macrobrachium species are included.
A possible practical use of compensatory growth, subjecting Piaractus brachypomus at different weekly feeding and fasting frequencies was sought. For this purpose, 450 individuals with an initial average weight of 20 g, arranged in five treatments with three replicates, were used. T1 = feed to satiation 5 days and fasting for two days; T2 = feed to satiation 6 days and fasting one day; T3 = feed to satiation 7 days; T4 = fasting 14 days and subsequent feedback to satiety and T5 = power following the manufacturer's recommended food tables. Individuals of T1 treatment had the final weight and instantaneous growth rate lowest results compared to T2 and T3. This meant that fast two days a week influenced growth negatively, but the one-day fast (T2), did not affect it. The daily highest feeding rate was present with treatment T4 but only relative to T3 and T5, due to a voluntary increase in food intake after the fasting period. By contrast, there were no differences between the T1, T2 and T3, which indicate that individuals of T1 and T2 treatments, voluntarily increased intake after fasting days equaling intake T3 treatment. The body composition of the fish was not affected by the treatments, so that after refeeding, all reserves used during fasting were restored. The values of protein and energy retention were better with treatment T5, because it used less food and its growth was similar to the other treatments. These results indicated that feeding could be deleted in one day but increasing ration during the rest of the week. However, the T5 results are relevant to the cultivation of the species, since the production cost of each kilogram is low and net profit is higher.
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