The tarpon (Megalops atlanticus) Costa Rica. is among the most highly sougth inshore gamefish in the Caribbean coast of Costa Rica. Adults individuals were collected in a period of 23 months (1990-1992), in the Barra del Colorado area, northeast of Limon province. A variety of morphometric and meristic and some biological observations have been re­corded from 113 fishes collected; the maximun standard length (SL) observed was 1820.00 mm and the minimum SL was 845.00 mm; the minimun weight (Wt) was 7.00 kg and the maximum Wt observed was 74.00 kg; the gonadal­ somatic index (GSI) mowed a trerid with two maximum for males and females respectively. 240 juveniles and 107 leptocephalus were collected in Don Nati Creek station located in Limon southeast coast in a period of 50 months (1988-1992), the temporal patterns in juvenile recruitment showed a maximum in December to February and July to October to metamorphic leptocephalus.De este modo, el objetivo final de este trabajo es describir la estructura morfométrica y algunos otros aspectos biológicos de la pobla­ción adulta de M. atlanticus; para la fase larval y juvenil los objetivos fueron; describir la ex­tensión del hábitat de los estadios tempranos en Costa Rica y estimar los patrones temporales de reclutamiento.