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Influência da frequência alimentar durante a alevinagem do pacamã (Lophiosilurus alexandri) Frequency of feeding for fingerlings pacamã (Lophiosilurus alexandri

O levantamento da qualidade de água pode ser um indicador que auxilia o diagnóstico ambiental de recursos hídricos necessários em ambiente periurbano. O presente trabalho teve como objetivo avaliar a qualidade microbiológica da água de nascente localizada no córrego Siriema (setor intermediário) no município de Jandaia do Sul-Paraná. Em campo, foi coletado amostra de água da nascente na margem direita (23º 35' 18" S e 51º 38' "22 O), situada na região próxima à rua. A análise

- An experiment lasting 180 days was carried out to evaluate the influence of sex on the performance and production of silver catfish (Rhamdia quelen) when reared in closed recirculation systems using only males, only females, or with both genders. A total of 300 fish (41.49 ± 6.82 g and 16.53 ± 0.95 cm) were used, comprising 150 females and 150 males distributed in an experimental structure consisting of three closed water recirculation systems coupled to a 20,000 L culture tank and a 20,000 L biofiltration tank connected by a 3,500 L h-1 water pump. The first system contained 100 females, the second, 100 males, and the third, 50 females and 50 males. High fish weight variations were observed regardless of sex. Female weight gains and specific growth rates were 41.51 % and 28.94 % higher compared to males, respectively, exhibiting greater growth than males raised monosexually or in mixed rearing systems, with no effect on chemical composition or trunk yield. The findings thus indicate that both male and female silver catfish exhibit wide weight variations and females that gain more biomass than males reared monosexually or in mixed-sex systems.