Abstract: From the viewpoint of behavioral ecology, a pilot study was made on the mating capacity of male Macrobrachium rosenbergii with different morphotyp
es (blue claw, BC; orange claw, OC; runt or small male, SM) native to the Pusur River in Chalna County of Khulna Division, Bangladesh. No significant differences were observed in the mating behavioral modes among the male morphotypes, but the time invested in such typical mating behaviors as pre-/postcopulatory mate-guard and copulation/spermatophore transfer for BC, OC and SM had distinct difference. BC spent much less time than OC or SM on precopulatory guard (PG) and spermatophore transmission (ST), but much more time on post-copulatory guard. SM spent the longest time on PG and ST, and the shortest time on postcopulatory guard. The average frequencies of successive copulation in 120 h were respectively 4.6, 2.2, and 1.3 at the sex ratio of 8∶1 (♀∶♂) in BC, OC and SM when the body mass of the females was 80 percent of the males. BC possessed much stronger capacity of successive copulation. The mating capacity of male M. rosenbergii was not only related to its own body mass, but also related to the body mass of female M. rosenbergii. Only when the males and females matched to some extent in their body mass, could the copulation be guaranteed in success. Otherwise, false copulation would occur.

Key words: Macrobrachium rosenbergii, male, morphotype, mating capacity, environmental problems, urban metabolism, prior modes, urban ecosystem.