A total of 245 individuals from a population of the endemic Bermuda killifish Fundulus bermudae in anisolated anchialine pond (Mangrove Lake) were trapped between November 2004 and November 2005.Laboratory analysis of gonad development allowed determination of the seasonal reproductive cycles ofboth females and males. A distinctive annual pattern was evident, with female and male gonadal cyclessynchronous throughout the study period. The results indicate that the F. bermudae males and females begantheir spawning season in February, but reached primary peaks in May and June respectively. Gonadalindices abruptly fell after June and continued to fall at a steady rate until September, marking the end ofthe spawning season. Gonad recrudescence, as indicated by basal gonad indices, occurred in Septemberand lasted throughout the autumn and early winter months.