I call BS
...on the last paragraph, "The Canadian province of Alberta has almost declared the critters an invasive species as so many of them seem to have survived being flushed down the lavatory and currently infest the region's storm drains"
1. Fact check: lavatories aren't connected to storm drains. If they were, every river would be an open sewer, and imagine what river mouths would look like.
2. If that last statement was supposed to read "...infest the regions sewers" that's even more unbelievable because the only things that can survive in a sewer is bacteria. Goldfish may be tough, but there's NO WAY they are going to survive in raw sewage.
3. Sewers (and storm drains) are not closed, static systems - they lead somewhere: rivers (and the sea, eventually) in one case and treatment plants in the other. Goldfish can't survive in salt water, either, and (depending on the treatment process) I doubt it's likely the sewerage farm will do them any good.