Kota Kinabalu: 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.
Sabah Minister of Agriculture, Fisheries and Food Industry Datuk Jamawi Jaafar said rising river water temperatures over the past two to three weeks had also made the virus more aggressive in attacking pelian fish.
He said although koi fish were released into rivers to enhance the appearance of tagal areas, the practice was a mistake that has affected 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,” he said.
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.
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On community efforts to curb the spread of KHV, Jamawi said he had recently witnessed the strong commitment of Kampung Luanti villagers near Ranau in conserving pelian fish in their waters.
He said he was informed that villagers were using traditional methods such as garlic, believed to help reduce the impact of the viral infection.
According to him, such efforts reflect growing public awareness of the importance of conserving pelian fish from the threat of extinction.
In a related development, Jamawi said the Ministry was also monitoring the presence of pleco fish (ikan bandaraya) in several rivers and tagal areas in the State, as the species had already been detected in some locations.
“The pleco fish was originally kept in aquariums, but some individuals released it into rivers when they could no longer care for them. It is now becoming a threat to native fish,” he said.
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.
The move is part of ongoing efforts to address cases of pelian fish deaths linked to KHV infection, which have been reported since Aug 1, 2025.
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