The objective of this research was to determine the insemination dose for artificial fertilization and describe the embryonic development of tambaqui (Colossoma macropomun). The gametes were collected from induced breeding hormonally. An artificial fertilization was performed with different sperm/oocyte ratios of D1-50666, D2-75999, D3-101 332, 126 665-D4, D5-151 998 sperm/oocyte. Embryonic development was monitored through periodic stereoscopic observations until hatching. When embryos reached the blastopore closure stage, the rate of fertilization in different insemination doses was calculated. A regression equation was estimated to determine the ideal proportion of the gametes. The fertilization rate increased linearly according to the equation Ŷ = 0.050 + 0.00000773 X (R² = 97.5), up to the proportion of 102.486 spermatozoa/oocyte, and, from this point, the fertilization rate was maintained at 84%. The embryonic development of tambaqui was meroblastic discoidal, as expected from telolecithal eggs and we recommend the use of the insemination dose of approximately 100.000 sperm/oocyte in the artificial fertilization of tambaqui.
tambaqui; embryology; spermatozoa; reproduction
