Invasive Goldfish

The humble goldfish seems like one of the most harmless and innocuous pets that it’s possible to get. Peacefully feeding and swimming around and emitting the occasional bubble, it’s hard to imagine that your aquatic friend could pose a threat to anyone, let alone an entire ecosystem. Yet conservationists in Australia have found that because of their huge popularity in domestic aquaria, unwanted goldfish are fast becoming a big problem in the wild.

When faced with the prospect of a goldfish they no longer want (or are able) to keep, many households in Australia are simply dumping their former pets into their nearest local waterways and wetlands. In most cases, the fish are released innocently as a seemingly humane alternative to euthanasia, however, the former domestic fish have survived and thrived so well that they are now an invasive species and are choking the local habitat for native fish.

Specimens as large as 1.9kg have been found by scientists studying their impact on local aquatic habitats, and evidence is mounting that they’re doing a similarly large amount of damage. Besides causing algal blooms, disrupting aquatic plants and eating other fish’s eggs, the monster goldfish have been suspected of introducing previously unknown diseases.

So it’s clear that while many people may think that releasing their goldfish in this way is a humane and harmless act, the fact is that they can end up wreaking havoc on native fish and scientists have warned people to think twice and never release their pet fish into the wild.