Goldfish are everyone’s favorite training pet… until they’re not. As The Telegraph reports, giant, football-sized goldfish are being found in one Australian river.

Goldfish are a ubiquitous pet thanks to the low bar for care, and their compact size, but also because their lifespan is relatively short, perfect for the notoriously short attention span of children. While most of the little fish die early deaths in their tiny bowls, a significant number of the creatures are “humanely” released into local waterways when their owners grow tired of them.

However the unfortunate truth is that goldfish, originally native to Asia, are a powerfully invasive species in the wild, and will grow quite large in unfettered conditions. And Australia’s Vasse River is apparently being taken over by the former carnival pets. The Vasse, a nutrient rich habitat for the former pets, has started producing huge specimen, likely started from dumped fish.

Researchers have found that the fish can roam as far as 230 kilometers to breed, spreading their habitat, and growing all the way. Unfortunately their explosive growth can also leech an inordinate amount of resources from the ecosystem, as well as running the risk of spreading disease.

All of these real world concerns aside, there is still something a bit magical about giant goldfish.