The objectives of this study were to determine the basic parameters of lake minnow, Eupallasella percnurus (Pall.), semen in terms of sperm concentration, seminal plasma composition, and sperm motility. Although E. percnurus milt characteristics are similar in many respects to those of common carp, Cyprinus carpio L., distinct species-specific differences were noted. The semen was characterized by its minute volume (~ 9 μl), and one of the highest sperm concentrations (21 × 109 ml-1) among teleosts. Osmolality was relatively low (~ 235 mOsm), perhaps due to urine contamination. The anti-trypsin activity (~ 64 U l-1) and protein concentration (~ 0.5 mg ml-1) was one of the lowest noted among fish. E. percnurus semen was characterized by a high proportion of motile sperm (~ 89%) and relatively high straight-line velocity (93 μm s-1). The parameters of sperm trajectory were within the range typical for cyprinid sperm. A characteristic feature of the semen was its stickiness, which manifested in agglutination during storage. These preliminary results are the first to describe the basic parameters of E. percnurus semen. This information will be useful in work to develop a methodology for the short and long-term storage of semen in the active protection of this endangered species.
