Resfriamento de embriões de tambaqui (Colossoma macropomum) em diferentes tempos de estocagem

Abstract

The technique of cryopreservation of fish embryos has not efficient results yet, however, the cooling of embryos has been used with satisfactory results. The aim of this study was cooling embryos Colossoma macropomum subjected to a temperature of 2oC at different times of storage. Embryos were used in the following embryonic stages: blastoderm - 1.2 hours post-fertilization (hpf), epibolia - 5-hpf; closing blastopore - 8-hpf; appearance of the optic vesicle - 13 hpf. One hundred embryos, of each stage of ontogeny selected, were treated with glucose 0.5 M solution with 10% methanol, glucose 0.5 M with 10% methyl glycol and glucose 0.5 M in dimethylsulfoxide (DMSO) and cooled at 2°C for 6, 8, 10 and 12 hours. Statistical analysis was performed by ANOVA and Tukey test with 5% significance. We observed a significantly higher difference in complete development of live larvae with the group treated with methanol solution of glucose and a greater survival in the embryos at earlier developmental stages (8-hpf and 13-hpf). It is concluded, therefore, that the embryonic stages of closing blastopore (8-hpf) and appearance of the optic vesicle (13 hpf) can be considered the most recommended for use in cooling protocol of embryos of C. macropomum maintained for 8 hours at 2°C. Key words : Aquaculture, fish of South America, embryonic development, cryoprotectants, larval survival, storage.