Histological and hormonal changes towards the spawning season of female killifish fundulus heteroclitus from the great bay in New Jersey U.S.A

Fundulus samples were collected on monthly basis during the period from February 2015 until May 2015 There was a significant increase in the gonadosomatic index started in March and continued in April and May. Spawning seem to have started in March because large proportion of oocytes were at the ova stage and there were also calyxes of ovulated follicles. Thyroid stimulating hormone (TSH), follicle stimulating hormone (FSH) showed variations that could be attributed to the physiological processes involved during the different stages of oocytes maturation.