Preliminary observations on the effect of sudden changes of temperature on survival of young Matrinxã (Brycon cephalus) under laboratory conditions

Abstract

Matrinxã is a very promising amazonian fish for fish culture in Brazil. This study is aimed at determining the approximate tolerated temperature range in this species. Groups of ten young matrinxã specimens (15.1±0.8 cm average length and 58.3±10.3 g average weight) were subjected to 9 different temperatures for 24 hours without previous acclimation. Fish were transferred from an initial temperature of 27ºC to those ranging from 12 to 39ºC at 3ºC intervals. Both 12ºC and 39ºC temperatures were lethal for this species with 100% mortality rate. Following 2 minutes of exposure to 39ºC fish changed behavior, showing an increase in opercular movements and erratic swimming; mortality reached 100% after 18 minutes. At 12ºC, fish lost equilibrium immediately after exposure and started swimming erratically; after only 4 minutes fish became lethargic and remained immobile on the bottom of the tank. Total mortality was only evident following 24 hours. At 15ºC matrinxã lost equilibrium after 5 to 6 minutes of exposure but mortality was only 20% after 24 hours. Fish tolerated well temperatures ranging from 18 to 36ºC with 100% survival after 24 hours. This preliminary study suggests that temperatures between 18 and 36ºC are the approximate range normally tolerated by this species, although survival at other temperatures may be increased by gradually acclimating fish to the more severe increases or decreases in temperature. In addition, it indicates that matrinxã may be cultivated over a wide geographical area.

Cardiorespiratory responses to graded hypoxia in the neotropical fish matrinxã (Brycon amazonicus) and traíra (Hoplias malabaricus) after waterborne or trophic exposure to inorganic mercury

“…On the other hand, B. amazonicus (Characiformes, Characidae) is a rheophilic species native from the Amazon basin that inhabits clear and well oxygenated waters. It is an omnivorous fish that grows very fast feeding on artificial diets, and is resistant to handling and poor water quality, as in hypoxic conditions when the fish develops a dermal extension of the inferior lip to perform aquatic surface respiration -ASR (Guimarães and Storti Filho, 2003).…”

Physiological stress responses in the warm-water fish matrinxã (Brycon amazonicus ) subjected to a sudden cold shock

“…We pushed fish very close to their tolerance limits. Guimarães & Storti-Filho (2003) exposed matrinxã to a range of temperatures (from 12 to 39 o C) and demonstrated that the Physiological stress responses in the warm-water fish matrinxã (Brycon amazonicus) subjected to a sudden cold shock low temperature limit was 18 o C. The authors also showed that at 15 o C mortality started to occur immediately after the transfer to the cold-water. Further research is necessary to determine whether a long-term cold shock would elicit a physiological response in matrinxã.…”