Where do Shadowhiskers actually come from?

In the level 55 Fishing quest 'Invasion of the Supper Snatchers' the player is tasked with catching 3 Shadowhiskers.

The Tailfeather hunter you speak to mentions "They ain't native to this area, see-some lunkhead hunter decided to bring them in special when no one was looking, and set them free in the river"

I've tried searching but these 'Shadowhiskers' are nowhere to be found outside of the Dravanian Forelands.

So, question is, where do the Shadowhisker fish originally come from?

Coerthas judging from the fishing log entry.

That's about all we can assume, seeing as it can't be fished from anywhere else.
Although, thinking about it now, Coerthas Western Highlands was only made all icey after the calamity, perhaps it originated there and has since become extinct in it's home region?
Case closed for now, I guess.

Welcome to fishing lore: way deeper than you expect! If you ever have a question about a fish, the fishing guide will answer it. ...or perhaps just raise further questions. That last one happens a lot, actually.

This isn't even the only fish that was affected by the Calamity. Also affected were the ocean fishing-found Shooting Star (driven to near-extinction) and La Noscean Jelly (huge population explosion), and the Warmwater Trout (native to La Noscea, but the Calamity caused a partial migration to the Thanalan). The fact that last one exists means that, yes, that one comic was right: the Calamity did affect the troup population!