The development of the digestive system in larvae of the Neotropical fish P. argenteus was analyzed histologically. On the 3 rd day after hatching, the digestive system comprised oropharyngeal cavity, esophagus and simple undifferentiated tube. Since secreting cells, positive to Alcian Blue (AB), were found in the esophagus, digestive activity in the initial phase had occurred. On the 18 and 28 th days after hatching, the esophagus was positive for AB and Periodic Acid Schiff (PAS) stain. The stomach was fully differentiated, with the cardiac, fundic and pyloric regions. Different regions of the epithelium were characterized by basic and acidic secreting cells (AB and PAS positive). On the 18 and 28 th days after hatching, the intestine was long, coiled and divided into proximal, middle and distal segments with pyloric ceca. Secreting cells in different regions of the gut were either positive or negative for AB and PAS. Results showed that larvae of P. argenteus exhibited digestive activity on the third day after hatching, with fully differentiated stomach and intestines on the 18 and 28 th days and their different regions featuring secreting cells.
ResumoA avaliação da proporção ideal de concha calcária/brita em biofiltro no cultivo de pós-larvas de tilápia do Nilo foi o objetivo deste trabalho. O experimento foi realizado no Laboratório de Aquicultura e Ecologia Aquática da Universidade Federal dos Vales do Jequitinhonha e Mucuri -UFVJM, entre os dias 21 de julho a 3 de agosto de 2011. Pós-larvas de tilápia do Nilo na densidade de 13,3 pós-larvas/L foram cultivadas em aquários contendo biofiltros com 100% concha calcária; 70% concha calcária/30% brita; 50% concha calcária/50% brita; 30% concha calcária/70% brita; 10% concha calcária/90% brita; 100% brita e como controle, aquário sem biofiltro, em DIC, totalizando sete tratamentos com três repetições. A presença de concha calcária no biofiltro proporcionou melhores condições da água, quando comparado com os aquários sem biofiltro e com brita apenas, mantendo os parâmetros adequados para o cultivo de tilápia do Nilo. Apesar dos níveis de amônia estarem próximos ao limite superior desejado para o cultivo da espécie, eles não comprometeram o crescimento (comprimentos total e padrão, altura e peso). A proporção 30% de concha calcária e 70% de brita é recomendada como substrato de biofiltro, por apresentar a melhor taxa de nitrificação ao longo do experimento. Palavras-chave: biofiltração, larvicultura, nitrificação, resíduos nitrogenados, Oreochromis niloticus. AbstractThe evaluation of the optimal ratio of calcareous shell/gravel substrate in biofilters was evaluated in post-larval culture of Nile tilapia the was objective of this work. The experiment was conducted at the Laboratory of Aquaculture, UFVJM University, Brazil, from July 21 to August 3, 2011. Post-larvae of Nile tilapia at density 13.3 post-larvae/L were grown in tanks containing biofilters with 100% calcareous shell; 70% calcareous shell/30% gravel; 50% calcareous shell/50% gravel; 30% calcareous shell/70% gravel; 10% calcareous shell/90% gravel; 100% gravel; tank without biofilters and control, in completely randomized design with seven treatments and three repetitions. Calcareous shell provided better water conditions than tanks without biofilter or containing only gravel, keeping the parameters suitable for Nile tilapia farming. Although ammonia levels were close to the desired upper limit, they had no influence on morphological parameters (total length, standard length, height and weight). The rate 30% shell/70% gravel is recommended as biofilter substrate, as it provided the best nitrification rate during the experiment.
1Two experiments were carried out to study piabanha-do-Pardo (Brycon vonoi) larvae development. In the first, six different diets were evaluated, being Artemia sp., plankton, feeds, feeds + Artemia sp., feeds + plankton, and Prochilodus hartii (curimba) larvae. In the second, four different water salinity levels (0, 2, 4, and 6‰) were tested. Both assays were entirely randomized design experiments, lasting for 10 days. At the end of these trials, fish biomass, survival, total length, weight, and specific growth rate were measured. Additionally, water quality, temperature, oxygen, pH, and electric conductivity measurements were made every three days. The curimba larvae diet presented higher survival rate (47.2%) and biomass weight (2.5 g) than the other diets, which were similar among each other. Piabanha-do-Pardo larvae weight, length, and specific growth rate varied with the offered diets. All water salinity treatments showed better results than those observed for fresh water. When cultivated in 2‰ salinization, larvae had 52.5% survival rates and 0.49 g biomass weight, while in the fresh water these results were 6.6% and 0.23 g, respectively. To conclude, we may identify curimba larvae as an adequate diet, and a 2‰ water salinity as recommended if Artemia sp. larvae are fed to piabanha-do-Pardo larvae. Combinações de alimentos e salinidade da água na larvicultura de piabanha-do-Pardo (Brycon vonoi, Lima 2017)Foram conduzidos dois experimentos com larvas de piabanha-do-Pardo Brycon vonoi. No primeiro ensaio, avaliaram-se seis dietas: Artemia sp., plâncton, ração, ração + Artemia sp., ração + plâncton, larvas de Prochilodus hartii (curimba). No segundo, quatro salinidades de água (0, 2, 4 e 6‰), ambos os experimentos em delineamento inteiramente casualizado, com duração de 10 dias. A biomassa, sobrevivência, comprimento total, peso e taxa de crescimento específico foram mensurados ao final dos experimentos; já os parâmetros de qualidade de água, temperatura, oxigênio, pH e condutividade elétrica foram aferidos a cada três dias. O alimento larva de curimba resultou em maior sobrevivên-cia (47,2%) e biomassa (2,5 g) do que os demais tipos, que foram similares entre si. O peso, o comprimento e a taxa de crescimento específico não diferiram entre si para as larvas alimentadas com os diversos tipos de alimento. Todos os tratamentos com salinização apresentaram melhores resultados em relação a água doce sem salinização. No entanto, quando cultivadas sob 2‰ de salinização, as larvas apresentaram 52,5% de sobrevivência e 0,49 g de biomassa, e em água doce sem salinização foram observados apenas 6,6% e 0,23 g, respectivamente. Conclui-se que a utilização de larvas de curimba como dieta é o mais adequado e recomenda-se salinizar a água com 2‰, caso seja fornecida artêmia como alimento.Palavras-chave: Artemia sp.; canibalismo; characiformes; espécie nativa; manejo alimentar; Prochilodus hartii.
Nile tilapia performance fed with diets containing crambe meal supplied with enzyme complex SSF was evaluated. With initial average weight ranging between 1.133g ± 0.105, 280 Nile tilapias were randomized into seven treatments, with four replicates and 10 fish per tank, totaling 28 experimental units. The temperature-controlled recirculation system had 30 L per tank, with individual water supply and aeration. The physico-chemical parameters of the water (temperature, dissolved oxygen, ammonia and pH) were monitored periodically. The fish went through an adaptation period of one week prior to starting the trial. The treatments consisted of a control diet and others diets containing three levels of inclusion of crambe meal, being replaced in their proper proportion, the protein soya by the protein ingredient evaluated (5, 10 and 20%) with 500 ppm of enzyme complex SSF or not. The isoproteic diets (360 g.kg-1) contained the same amount of the ingredients, changing only the levels of inclusion of soya meal, crambe meal and inert. Fish were fed ad libitum four times per day. At 56 days, the tilapia performance was evaluated. The physic and chemistry parameters of water were within of the levels recommended for the species during all experimental time There was statistical difference for final weight, weight gain and feed conversion. It is concluded that the inclusion of up to 10% crambe meal supplemented with 500 ppm of enzyme complex SSF provides better performance and higher nitrogen retention for Nile tilapia.
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