WATER TEMPERATURE EFFECTS ON GROWTH, FEED UTILIZATION AND SURVIVAL OF BLACK PACU (Colossoma macropomum) FINGERLINGS

Abstract

Ectothermic organisms normally live within a specific interval of thermal variation and life outside of that interval can be extremely difficult or lethal. Aquacultural use of black pacu Colossoma macropomum has expanded to diverse areas with various climatic conditions. In the past few years, practical aquafeeds have been evaluated striving to improve the performance of Amazonian fish, but there is little information regarding environmental effects on black pacu growth, feed intake and utilization. This lack of information, limits the ability to optimize the dietary intake and feed utilization, and makes it difficult to plan for future temperature changes. The goal of this study was to evaluate and compare black pacu fingerling growth, feed utilization and survival when reared at three water temperatures: 27.5, 30 and 32.5 ºC. Ninety fingerlings (1.38 ± 0.03 g mean total weight) were distributed in groups of 10 individuals and placed into nine 30-L volume fiberglass tanks. Fishes were submitted to a 7-day acclimation period before initiating the 21-day rearing trial. Fish reared at 30 ºC demonstrated significantly higher final body weight, body weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio levels than fish reared at 27.5 and 32.5 ºC (P<0.05). No significant differences (P>0.05), were recorded for feed intake, protein intake, or condition factor. This study suggests temperature increase may impair the ability of black pacu to utilize feed and culturing at water temperatures above 30 ºC may be limiting for this fish.

Thermal biology of tambaqui (Colossoma macropomum): General insights for aquaculture in a changing world

“…Lapointe et al 52 and Amanajás et al (in preparation) found increased mortality and decreased specific growth rate, respectively, at 15 and 21 days of cultivation at 35°C. According to Chu‐Koo et al, 53 temperatures above 32°C increase consumption, decrease food conversion efficiency and can impair species growth during 21 days of cultivation. However, the effects of temperature seem to be modulated by simultaneous exposure to darkness.…”