Kullander, F. (Freshwater Fish Red List Authority) & Smith, K. (IUCN Freshwater Biodiversity Assessment Unit)
Justification: Sinocyclocheilus grahami is endemic to Lake Dianchi (surface area 292.6
km²), Yunnan Province, China. It used to be a very common and important
commercial fishery species, but it has undergone a massive population decline
from around the mid 1960s and totally disappeared from the lake body in the
1990s. The species was very common and supported a high harvest in the lake
before the 1960s; it is now suspected that the population has declined by at
least 80% over the past three generations (since 1992; estimated generation
length is five years). Scientific surveys, carried out since 1999, have found it
only existing in some tributaries and springs. There are four subpopulations
known which are separated (severely fragmented) from each other by the polluted
lake body. Major threats to the species are introduced species, overfishing and
pollution from agriculture and domestic sources which have led to high levels of
nutrients and eutrophication in parts of the lake.
Endemic to Lake Dianchi its tributaries and springs. Now the species is extirpated from the lake itself, and is only known to survive in 20 temple spring ponds, and one lake tributary (Muyang/Lengshui) all within 36 km of the lake shore.
Known from about 20 temple spring ponds, and one lake tributary (Muyang/Lengshui) = four subpopulations. However the temple springs may be connected by small underground karst rivers. There are still a big portion of rivers and reserviors that has not been investigated, so the population size outside of the lake is impossible to estimate.
Clear water usually with indigenous macrophytes such as Ottelia acuminata or Hydrilla verticillata. When water quality in the lake was better it is believed it breeds only in the spring waters. Needs flowing water to breed, laying its eggs on hard substrates (sand to rocks, not mud or silt). Breeds from January to April. In winter it appears to migrate into cave streams. Adults eat shrimp and small fish, and juveniles eat zooplankton. They like water temperature about 20°C.
Its loss from the lake is likely due to introduced fish species, declining water quality, loss of macrophytes (in part due to grass carp), over-fishing, and also breeding sites lost due to siltation and blocked access.
Current threats to the springs are introduced species (especially rainbow trout and red-eared slider turtle); also land use adjacent to springs and modification of spring structure.