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Quatrocentos alevinos de tilápia-do-nilo (Oreochromis niloticus) foram criados em sistemas de bioflocos, com uma relação carbono:nitrogênio 10:1 durante cinco semanas com objetivo de analisar o desempenho zootécnico da tilápia-do-nilo, os parâmetros de qualidade de água (oxigênio dissolvido, temperatura e quantidade de flocos, amônia (total e tóxica), pH, nitrito, nitrato, alcalinidade e sólidos suspensos totais) e a análise nictemeral (temperatura, oxigênio e pH) no 5º e 35º dia de cultivo durante 24 horas. Concluindo que os parâmetros se mantiveram similares entre o 5º e 35º dia de cultivo.

Fish species assemblage and selected environmental variables were monitored in Lake Volta from September 2014 to August 2016 to determine seasonal variability in species composition, catch and environmental variables that determine the structure of the fish community. A total of 1,557 individual fish belonging to 41 species, 25 genera and 13 families were recorded. The important fish species with respect to frequency of occurrence, abundance and weight, respectively, were as follows: Chrysichthys (100%; 43.03%; 17.93%), tilapias (100%; 28.97%; 17.86%), Alestes (100%; 14.13%; 32.10%) and Bagrus (91.67%; 5.65%; 12.80%) in that order. The composition of fish species and their temporal variation in experimental catches were similar to that of commercial catches. There were no significant differences (p > 0.05) in species abundance, weight and diversity indices between the dry and wet seasons. The modal class of length frequency distribution of the dominant species in the catch, Chrysichthys, reduced from 125 mm in 2006 to 95 mm in the current study indicating overfishing. Environmental variables considered showed little variation and within optimal ranges for fish survival and did not differ significantly between seasons. Canonical Correspondence Analysis showed that environmental variables explained 43.30% of the variation in species abundance with Lake water level, nitrite-nitrogen and total dissolved solids being the main environmental factors influencing the structure of the fish community.

Plesiomonas shigelloides es un bacilo Gram negativo, anaerobio facultativo, móvil, que pertenece a la familia Enterobactereaceae. No forma parte de la flora normal del humano, mientras que los peces dulceacuícolas como las tilapias se tienen como su reservorio primario. Considerando: a) La implicación cada vez más frecuente de este microorganismo como agente causal de enfermedades intra y extra intestinales, b) El incremento de la comercialización de tilapias silvestres y de cultivo a nivel nacional y c) La necesidad de métodos de detección e identificación rápidos y efectivos de patógenos, se aplicó el método biomolecular de la Reacción en Cadena de la Polimerasa (PCR). Se procesaron mediante la PCR, cepas de P. shigelloides y homogeneizados de pools de bazo, riñón y cerebro, y de intestino de tilapias, utilizándose oligonucleótidos iniciadores específicos para el gen 23S ARNr de P. shigelloides. Se obtuvo el reconocimiento del 75% de las 20 cepas identificadas por pruebas fenotípicas convencionales, detectándose además en 27% de los homogeneizados frescos y en 18% de los congelados. Estos resultados confirman la especificidad del método para la identificación de diversas bacterias potencialmente patógenas, su utilidad en el mejoramiento del sistema de control de calidad de granjas dulceacuícolas y en el estudio de casos clínicos, aumentando la efectividad del sistema de salud relacionado con estas áreas. Plesiomonas shigelloides is a Gram negative rod, facultative anaerobic, motile, that belongs to the Enterobacteriaceae. It’s not part of the normal human flora, while fresh water fish like tilapias are thought to be its primary reservoir. Considering: a) The more frequent implication of this microorganism as the causal agent of intra and extraintestinal infections, b) The wide spread of national commercialization of feral and cultured tilapias and c) The need for rapid and effective detection and identification methods, the biomolecular technique of Polymerase Chain Reaction (PCR) was applied. Strains of P. shigelloides and pools of homogenates from spleen, kidney and brain and the intestine of tilapias were processed by PCR, using specific primers for the gene 23S rRNA of P. shigelloides. The 20 strains identified by conventional phenotypic traits were identified in 75%, additionally it was detected in 27% of the fresh homogenates and in 18% of the frozen ones. These results confirm the specificity of the technique for the identification of a diverse range of potential pathogenic bacteria, its usefulness in the improvement of quality control in freshwater farms and in the study of clinical cases, improving the effectiveness of health systems related with these areas. 459 - 465 Bimestral