Studies were conducted on the effect of clomiphene on ovulation and spawning in matureC. carpiopre‐treated with indomethacin. It was demonstrated that indomethacin caused a block to ovulation and spawning at two dose levels (5 and 10 μg−1g). This blockade could be overcome by two (10 μg−1g each) successive dosages of clomiphene given 7 and 31 h after the indomethacin treatment. When indomethacin and clomiphene treatments were given concomittantly, the inhibitory effects of indomethacin remained more pro