On the wild spawning grounds, the round gobies Neogobius melanostomus are subjected to different social cues, such as sex-separation and high fish density. We designed an experiment to stimulate natural social stress when fish are separated from opposite sex individuals and exposed to close proximity of same-sex conspecifics. We examined the effects of different sex compositions on aggressiveness and brain concentrations of arginine vasotocin (AVT) and isotocin (IT), as AVT and IT are known to be involved in aggressive interactions during reproduction. The round gobies were kept in three experimental groups: same-sex groups broken down into male-only and female-only groups and mixed-sex groups. In this study, males and females from same-sex groups showed overt aggression and competition. Separation stress stimulated aggressive responses in both sexes, but the link between brain AVT and IT concentration and aggressive behavior was evident only in male-only group. In the male-only group, AVT and IT levels were the highest. This study shows that sex composition of the social environment can affect aggressive behavior as well as AVT and IT concentration in the whole brain of the round goby.

在野生产卵场上，圆形虾虎鱼Neogobius melanostomus受到不同的社会暗示，例如性别分离和高鱼密度。我们设计了一个实验，当鱼从异性个体中分离出来并暴露于同性同种物种的附近时，可以激发自然的社会压力。我们研究了不同性别组成对精氨酸血管收缩素（AVT）和异氰酸酯（IT）的侵略性和大脑浓度的影响，因为已知AVT和IT参与生殖过程中的侵略性相互作用。轮状虾虎鱼被分为三个实验组：同性群体分为男性和女性群体以及混合性别群体。在这项研究中，来自同性群体的男性和女性表现出明显的侵略性和竞争性。分离压力刺激了男女的积极反应，但仅在男性人群中，大脑AVT和IT浓度与攻击行为之间的联系就很明显。在仅男性人群中，AVT和IT水平最高。这项研究表明，社交环境中的性别组成会影响aggressive鱼整个大脑的攻击行为以及AVT和IT浓度。