Sabah: The current hot weather and drought have been identified as key factors triggering the activation of Koi Herpesvirus (KHV), carried by koi fish, posing a threat to pelian fish populations in rivers and tagal areas in Sabah.
According to BERNAMA News Agency, Sabah Minister of Agriculture, Fisheries and Food Industry Datuk Jamawi Jaafar stated that rising river water temperatures over the past two to three weeks have made the virus more aggressive in attacking pelian fish. He acknowledged that the introduction of koi fish into rivers, intended to enhance the appearance of tagal areas, was a mistake impacting local aquatic biosecurity.
"This virus only affects pelian fish because scientific studies show both species are closely related. If not contained, it is feared the situation will persist," Jamawi stated. Tagal, a Kadazandusun word meaning 'forbidden', refers to a traditional natural resource management system in Sabah that prohibits fishing in designated river zones for a set period to allow fish to breed before being harvested for food and income by local communities.
Pelian fish, or Tor douronensis, is a local mahseer species found in Borneo, particularly in Sabah and Sarawak, and is commonly bred under the tagal system. Jamawi noted the strong commitment of Kampung Luanti villagers near Ranau in conserving pelian fish, with villagers using traditional methods such as garlic to reduce the impact of the viral infection.
In a related development, Jamawi mentioned that the ministry is monitoring the presence of pleco fish (ikan bandaraya) in several rivers and tagal areas in the state, given its detection in some locations. Originally kept in aquariums, the pleco fish poses a threat to native fish when released into rivers.
Last week, the Sabah Fisheries Department issued a special circular to all districts to implement immediate control measures against non-native fish species in the state. This initiative aims to address cases of pelian fish deaths linked to KHV infection, reported since August 1, 2025.