Not necessarily it seems. Some people even dispose of their aquarium fish in local waterways, where they can sometimes become a problem. In this case there is now a local population of Siamese Fighting Fish established in Fogg Dam at Humpty Doo - they are not a welcome guest!
The brightly coloured machisimo fish are beautiful in an aquarium but definitely an unwelcome invasive pest fish in the wilds of the NT, in freshwater dams and creeks. Fogg Dam is a lovely spot, a tourist drawcard just outside Darwin, but the fish seem to be well established and removal is probably unlikely.
No one is sure how they arrived in Fogg Dam, but the population seems to be developing and is well established according to media reports, as well as observations by locals. Dumped from an aquarium seems most likely.
|one colour type - Betta splendens - Siamese fighting fish|
They might look nice in an aquarium, but they are an invasive pest fish and unwelcome!