Lethal temperatures for Rhamdia quelen larvae (Pimelodidae)

Abstract

The lower and upper lethal temperatures (LT50) of R. quelen larvae were determined. The larvae were obtained from two spawning periods with hatching temperatures of 21 and 26ºC respectively. Larvae were placed in tanks at which the temperatures were either increased 1ºC every 15min, or reduced 1ºC every 20min until larval movement ceased. This temperature was then maintained for 96h. Minimum mortality (29.0 ± 1.5%) was observed in the larvae held at hatching temperatures. The lower LT50 were 15.01 and 16.72ºC, and the upper LT50 were 29.25 and 27.83ºC for the larvae hatching at 21 and 26ºC, respectively. Thus, apparently there is no difference with relation to temperature change tolerance between larvae hatched in both temperatures.

Supervivencia de larvas de cachama blanca, Piaractus brachypomus Cuvier 1818, sometidas a cambios experimentales de temperatura

“…La temperatura es un factor ecológico importante por los efectos directos que tiene en la supervivencia de los peces (Chippari et al, 2000). Es por esta razón que dentro de las actividades de siembra de larvas es necesario establecer los rangos de temperatura y el tiempo en el que se debe hacer la aclimatación.…”

Influencia de la temperatura en la sobrevivencia de larvas de Rhamdia sebae c.f. (Siluriformes heptapteridae)

“…La etapa del crecimiento en donde las respuestas se contienen en el rango de confort con intervalos más reducidos y efectos con manifestaciones más visibles, es la etapa de larva (Osse y Van Den Boogaart 1995). Los peces en este periodo, en el que prácticamente todas las estructuras y funciones están en pleno desarrollo o en transición, son especialmente susceptibles, frágiles y con reducidas capacidades de respuesta a los cambios de todo orden, en especial a los cambios medioambientales de temperatura (Chippari et al, 2000).…”

“…Las temperaturas inmediatamente por debajo y por encima del rango de confort (rangos de estrés), generan en las larvas respuestas de alerta con indicadores visibles como boqueo, inapetencia, cambio de color, lentitud de nado y otras (Morales,1986;Chippari et al, 2000). Los rangos de estrés en este trabajo, delimitados por el intervalo de sobrevivencia del 30-80%, fueron intervalos pequeños de temperatura similar a como lo expusieran Parker y Davis (1981) quienes notaron que tales rangos son mucho menos amplios que el rango de confort.…”

Development, nutrition, and rearing practices of relevant catfish species (Siluriformes) at early stages

“…The intensive indoor early culture of silver catfish can be conducted under controlled conditions in tanks, using clear water, controlled water temperature (21–26°C), 156 and protection from predators. In these systems, cannibalism was observed from first feeding at 2 dph and became more frequent after 6 dph.…”

“…In this regard, water hardness affects silver catfish performance. 154,155 In particular, when early juveniles were reared from first feeding during three weeks in water containing 30 and 70 mg CaCO The intensive indoor early culture of silver catfish can be conducted under controlled conditions in tanks, using clear water, controlled water temperature (21-26°C), 156 and protection from predators. In these systems, cannibalism was observed from first feeding at 2 dph and became more frequent after 6 dph.…”