To investigate the sperm ultrastructure and kinematic characteristics of Pareuchiloglanis anteanalis and Pareuchiloglanis gongshanensis， a systematic comparative analysis was conducted using scanning electron microscopy （SEM）， transmission electron microscopy （TEM）， and a computer-assisted sperm analysis （CASA） system. The results revealed that， although the spermatozoa of both species consist of an acrosome-less head， a midpiece， and a single flagellum， they exhibit significant divergences in morphological configuration and swimming patterns. The spermatozoa of P. anteanalis were relatively longer， characterized by a slender head （length-to-width ratio： 1.51）， a midpiece containing four umbrella-shaped， tightly arranged mitochondria， and a flagellum with symmetrical lateral fins. In contrast， the spermatozoa of P. gongshanensis were shorter， featuring a nearly spherical head （ratio： 1.08）， a midpiece with 4-5 smaller mitochondria， and a shorter flagellum with more developed lateral fins. CASA measurements revealed no significant differences in average path velocity （VAP）， straight-line velocity （VSL）， or curvilinear velocity （VCL） between the two species. However， P. anteanalis sperm exhibited significantly higher straightness （STR） and beat-cross frequency （BCF） （P<0.05）， resulting in a more linear swimming trajectory. Conversely， P. gongshanensis sperm showed a significantly greater amplitude of lateral head displacement （ALH） （P<0.05） and a more curved movement path. This study indicates that P. anteanalis sperm exhibit the classic “introsperm” phenotype adapted for internal fertilization， whereas P. gongshanensis sperm display traits characteristic of “aquasperm”， reflecting an adaptation to external fertilization.