Sand polychaetes (Perinereis nuntia) have been used as a live feed to boost reproductivematuration beforemating
in hatchery farms in Thailand. However, no study has evaluated the effect of polychaetes on performance and
physiology of the spermof the domesticated black tiger shrimp (Penauesmonodon). Therefore, this study aims to
study the effects of sand polychaetes on growth, survival, reproductive performance and sperm physiology and
morphology of domesticated male broodstock P. monodon. After feeding with either polychaetes or commercial
pellets for four weeks, growth and survival rates of polychaete-fed group were significantly higher than those of
pellet-fed group. Spermatophore weight and total sperm counts of the polychaete-fed group were significantly
higher than those of the pellet-fed group atWeeks 3 and 4, whereas % abnormal sperm cells and % acrosome reaction
of polychaete-fed groupwere significantly lower and higher than those of pellet-fed group only atWeek 4,
respectively. Physiology of spermatophores in the polychaete-fed groupwas white and opaque while that of the
pellet-fed group was pigmented. Morphological changes of sperm revealed less abnormal sperms (misshaped
half, misshaped head, and misshaped tails) in the polychaete-fed group. Nutritional analysis revealed that polychaetes
have significantly higher total protein, fat contents and essential fatty acids (arachidonic and
eicosapentaenoic acids) but significantly lower fiber content.Moreover, histological analysis of hepatopancreas revealed
more vacuoles,which are storages for glycogen and lipids in the polychaete-fed group than in the pellet-fed
group. Therefore, this study provides an evidence that polychaetes provide benefits to growth, survival and sperm
performance for boosting reproductive maturation in male domesticated broodstock Penaeus monodon.