Oh yes. I share this video here sometimes too. This devastation is the result of people dumping fish they don't want and won't take responsibility for, into non-native ecosystems.
It's a pretty horrifying watch, and it's hardly a rare event. Look at snakeheads that were dumped in the US. Goldfish are invasive all over the place, outcompeting native species and changing the ecosystems they invade entirely. People dump their kids "Goldie" when it's too big or the kid is bored of it, and think they're being kind. To that one fish. Better to euthanise it than to dump it into waters it doesn't belong in.
Someone once suggested that I dump some pest snails in the local creek instead of smushing them. I asked why would I do that? She said it would be more humane. I asked her if dying of starvation, predation or freezing to death was really more humane. Or if it would be humane to introduce a foreign pathogen to the local ecosystem?