Osteocheilus hasselti
Osteochilus hasselti is a common species that occurs throughout the survey range from the Thai-Lao-Myanmar border in the north, to the Mekong delta in the south. It appears to be a species that mainly lives in smaller tributaries and, during the onset of the flood season, migrates to flooded areas. At the end of the monsoon season, the species migrates back to its river habitats in tributaries and, to a lesser extent, the Mekong mainstream.
The number of developed eggs peaks in May-June, indicating that spawning occurs during the period of rising waters at the onset of the flood season.
Hypothesis:
Osteocheilus hasselti appears to constitute many subpopulations
throughout the Mekong basin, each undertaking short migrations
from rivers to flood-plain habitats at the onset of the flood
season, and returning to river habitats at the end of that period.