Huge goldfish are threatening Canada's ecosystem

This news may sound like an April Fool joke. However, it is extremely serious because of biological invasions (the uncontrolled spread of animals or plants outside of their native habitat), often leading to the extinction of an entire species and the destruction of an ecosystem.

Unfortunately, this is happening in Canada, where goldfish are threatening the underwater inhabitants.

Goldfish are widely accepted to be small, fragile, and harmless creatures. Still, few people realize that if they enter a natural reservoir, they start to multiply at the speed of light and disrupt the ecological balance. It is because goldfish have an unusual characteristic: they keep growing throughout their lives and, when living in the right conditions, can grow to the size of a cat. Moreover, the larger the reservoir they live in, the faster their growth. However, goldfish grow slowly in an aquarium, as they are constantly under stress due to living in such a small space.

Additionally, goldfish release hormones into the environment, which affect growth, both their own and that of other species. For example, the same hormone encourages the development of toxic blue-green algae and cyanobacteria that cause water blooms.

Canada's ponds have proven to be an extremely convenient habitat for goldfish. There are about 20,000 of the fish in Ontario, and they continue to breed! However, scientists fear that ongoing global climate change could reduce the oxygen content in bodies of water. If this is the case, regional fish species will begin to die. Simultaneously, naturally resistant to hypoxia, goldfish will start to replace them rapidly.