Larval survival and growth in Wallago attu (Bloch and Schneider): effects of light, photoperiod and feeding regimes

Growth and survival of dorado Salminus brasiliensis (Pisces, Characidae) post-larvae cultivated with different types of food and photoperiods

“…This strategy produced the better growth among treatments despite the fact that this species has been considered a typical visual predator. The results registered for dorado post-larvae survival and growth in LD 0:24 contrasted with other studies where better survival and growth were found with the increase of photoperiod, a response associated with various factors as the dependency of larvae visual abilities (Giri et al, 2002), the increase of predator-prey encounters (Puvanendran and Brown, 2002) and prey availability (Boeuf and Le Bail, 1999;Kestemont et al, 2003) and the insufficient time for the establishment of a robust rhythmicity plus the reduction of the standard metabolic rate (El-Sayed and Kawanna, 2004). Table 1 -Mean (± standard error) survival (%) and cannibalism (%) for dorado (Salminus brasiliensis) post-larvae, submitted to different photoperiods and fed with fish prey or Artemia nauplii after six-days of cultivation.…”

Crescimento e sobrevivência da tilápia chitralada submetida a diferentes fotoperíodos

“…Os dados de crescimento em peso e comprimento foram expressos por Wt = Φ×Lt θ , em que Wt é o peso total, Lt é o comprimento total, Φ é o fator de condição, θ é a constante; o coeficiente de variação é CV (%) = (100×S)/X; a taxa de crescimento relativo é TCR = (W F /W i ), em que W f é o peso final e W i é o peso inicial; a conversão alimentar aparente (CAA) = quantidade de ração fornecida (kg)/ganho de biomassa; e a sobrevivência é S = 100(n o indivíduos inicial)/n o indivíduos final. Os dados foram analisados conforme Mendes (1999 O "catfish" (Wallago attu, Bloch & Schneider) na fase de pós-larva apresentou melhor ganho de peso no fotoperíodo 12 horas de luz (Giri et al, 2002), resultado diferente daquele obtido nas pós-larvas de tilápia do presente estudo, em que o melhor ganho de peso foi no tratamento 24 horas de luz. No entanto, o controle apresentou o melhor desempenho quanto à sobrevivência, faixa essa também recomendada por outros autores para a tilápia-do-nilo e "catfish"…”

Effects of photoperiod on reproduction of Siamese fighting fish Betta splendens

“…Mortality during the experimental period did not show significant differences (χ2<0.01) between treatments nor was it connected to the photoperiod. Although the most frequent cause of death was due to confrontations between male and female during the mating, as observed by Howell et al (2003), other studies showed that very long photoperiods, especially the continuous light, showed higher percentages of mortality than long photoperiods (Sigholt et al, 1995;Appelbaum & Kamler, 2000;Giri et al, 2002;Adewolu et al, 2008).…”