thai Alien Fish Species in the Nan River Basin in Nan Province, Northern Thailand

Abstract

Exploration of fish fauna in the Nan River and 8 tributary of it in Nan province between 2003 to 2018 and followed by 104 stations. There were five orders, 6 families, 9 genera and 12 species identified. There nine species, Cirrhinus cirrhosus, Cyprinus carpio, Cyprinus rubrofuscus, Pterygoplichthys disjunctivus, Pterygoplichthys pardalis, Clarias gariepinus, Gambusia affinis, Poecilia reticulata and Oreochromis niloticus were imported, and three species, Leptobarbus rubripinnis, Oreochromis hybrid (red tilapia) and Channa micropeltes were introduced from other part of Thailand. There ten species, Cyprinus carpio, Cyprinus rubrofuscus, Pterygoplichthys disjunctivus, Pterygoplichthys pardalis, Clarias gariepinus, Gambusia afiinis, Poecilia reticulata Oreochromis niloticus and Oreochromis hybrid and Channa micropeltes were invasive alien species, and two species, Cirrhinus cirrhosus, and Leptobarbus rubripinnis were non-invasive alien species. According to the exploration, Oreochromis niloticus is distributed all rivers, followed by Clarias gariepinus and Cyprinus rubrofuscus were distributed 7 and 5 rivers respectively. The factor found alien species of fish in Nan River basin in Nan Province Caused by deliberately releasing and escaped from the rearing pond. The impact of alien fishes to native fishes and environment of Nan River basin in Nan province is not clearly in the long term, but in the exploration can collected larvae and juveniles of all alien fishes, shown that all its can be propagated in the river. Which if these fish to have more population and not control or remove them, may threaten native fishes and the environment of the River in Nan province in the future.