Cytochrome P450 aromatase (P450arom) plays a pivotal role in ovary development.In this study,we used semi-quantitative reverse transcription PCR (RT-PCR) to analyze spatiotemporal expressions of two P450arom genes (CYP1gA and CYP19B)and their responses to temperature stress in female yellow catfish (Pelteobagrusfulvidraco).Tissue distribution pattern of CYP19showed that CYP19B was abundantly expressed in fish brain and ovary (brain＞ovary),but weakly in intestines,whereas CYP19Awas exclusively expressed in ovary.Semi-quantitative RT-PCR analyses showed high transcript abundance of both CYP19A and CYP19B in the ovarian reproductive cycle,corresponding with serum estradiol-17β (E2) levels.Increases in aromatases,serum E2 and testosterone (T) levels in fish exposed to higher temperature indicated stimulation of ovarian maturation and recrudescence by heat stress in stages Ⅱ and V during the ovarian cycle,whereas associated decreases in stage III suggested vitellogenesis inhibition by heat stress.Gene expression of CYP19 was closely related to levels of serum E2.Results demonstrated CYP19 played a crucial role in the reproductive cycle of female yellow catfish.Different temperature stress affected CYP19 gene expression in the fish ovarian reproductive cycle.Associated P450arom genes could be useful for studying physiological aspects of yellow catfish.