The study examined how long-term low oxygen conditions (hypoxia) affect the spawning of mature common carp.
Hypoxia was found to decrease levels of luteinizing hormone (LH) in female carp, leading to delayed final oocyte maturation, even though the gonads and eggs developed.
Male carp also showed no courtship behavior under hypoxic conditions, suggesting that both hormonal changes and a lack of mating behaviors contribute to reduced reproduction in these fish.