Spawning of Schizopygopsis microcephalus (Cyprinidae) in the unique high-altitude conditions of the Tanggula mountains on the Tibetan plateau

Schizothoracine fish spawning habitats in the Tibetan Plateau are poorly understood but critical for conservation amidst anthropogenic threats and climate change. In a 2019–2021 study, we located the spawning grounds of Schizopygopsis microcephalus Herzenstein, 1891, at an astounding 4800 m above sea level, the highest known fish spawning site. This occurred in mid-June, before seasonal flooding. We found approximately six circular egg burial nests per square meter, measuring 20–30 cm in diameter and 10–15 cm deep, nestled within gravel (4–5 cm max diameter, D50 of 2.2 cm). Egg fertilization rates reached 98%, with an 82% hatching rate. Intriguingly, eggs displayed delayed shell hardening during natural incubation, possibly to protect against intense high-elevation ultraviolet radiation. Further investigations are needed to understand the role of the pliable membrane. Survival of the species requires that this kind of rare habitat be conserved.