The presentstudyinvestigatedthehormonesconcentrationsandgonadsalterationsof Clarias
gariepinus caused bysublethelconcentrationsof4-nonylphenol(0,0.05,0.08and0.1mg/l).The
changesintheactivitiesofthehormonesafterexposuretothesesubletheldosesof4-nonylpenol
referredtoendocrinedisruptionin Clariasgariepinus in associationwithhistopathologicalchangesin
reproductivetissues.Thelevelsofthyroidstimulatinghormone(TSH),triiodothyronine(T3),total
thyroxine(T4),folliclestimulatinghormone(FSH),luteinizinghormone(LH)andtestosterone
concentrationssignificantlydecreased(Po0.05) inthetreatedfishincomparisonwithcontrol.17-bestradiolincreasedsignificantly(
Po0.05) with4-nonylphenolconcentrationsincrease.Reductionin
the gonadosomaticindexwasevidentwithincreaseofsublethaldosesof4-nonylphenol.The
histopathologicalchangesofNP-treatedwererecordedingonadsof Clariasgariepinus reflectingtheir
sensitivitytoNP-estrogeniclikeeffects.