Sexual trait may simultaneously indicate sperm production and nutritional fitness in uniparental nest‐guarding fish: a case study on Amur sleeper

The reproductive success of uniparental males depends much on their nutritional stage (i.e. body condition). Therefore, secondary sexual traits should convey information not only fecundity but also stage. To test this hypothesis, we evaluate relationships between head crest height (HCH), as a trait, relative testes mass (an indicator sperm production), condition status) and Amur sleeper Perccottus glenii in two contrasting habitats. Furthermore, examined whether is pure investment to advertise male fitness – either females, rival or other fish approaching the nest it comprises some regainable energy well. We found that HCH closely related mass, especially at beginning period. consisted swollen connective tissue supraorbital region head, an oedematous epaxial muscle nuchal region. comprised adipose tissue, although assumed. argue represents reliable signal multiple aspects quality; indicates readiness spawn could potentially effectively facilitate female choice towards large with high great stage, which essential good guarding performance. Moreover, itself contribute nest-guarding performance by virtually enlarging size representing minor fat reserve.