Reproduction of the fish <span name="style_italic">Gymnothorax equatorialis</span> (Pisces: Muraenidae) in Jalisco and Colima, Mexico. A total of 707 <span name="style_italic">Gymnothorax equatorialis</span> were collected monthly in the Jalisco and Colima coast, Mexico, from December 1995 to December 1998 and from August to November 1999, in order to determine their reproduction patterns. Females outnumbered and had longer bodies (mean length 54.7 cm) than males (52.1 cm). The minimum, maximum and mean values of total fecundity were respectively 9 660, 99 992 and 32 029 eggs. The total body length at which 50 percent of individuals have ripe gonads (L50) was 43.7 cm for females and 42.7 cm TL for males. Ovaries had two main types of oocytes: small inmature in cromatin nucleolus phase (85.1 µm) and large mature in secundary vitellogenesis phase (701.6 µm). High numbers of spermatozoa were observed in the seminal tubes of ripe testicles, which presented a lobular development. Based in gonad features and temporal changes in the gonad-somatic index, it is concluded that <span name="style_italic">G. equatorialis</span> has two relatively short reproduction periods (at the middle and at the end of the year). Rev. Biol. Trop. 56 (1): 153-163. Epub 2008 March 31. has two relatively short reproduction periods (at the middle and at the end of the year). Rev. Biol. Trop. 56 (1): 153-163. Epub 2008 March 31.

Gymnothorax equatorialis; reproducción; temporada de reproducción; primera madurez; fecundidad; Costa de Jalisco y Colima