...It probably wouldn't have lasted the winter so good catch.
As counterintuitive as it seems, it's actually not that far-fetched considering the region.
Generally, temps here get too cold for tropicals in most waters from early to mid-September through May. However, that area of Idaho, northwest Wyoming, and southwest Montana is one of the most geothermally active regions in the world. There are bodies of water that have portions that maintain tropical temperatures year round, and other smaller bodies of water that maintain those temps completely, all due to being fed by hot springs. At one time, both guppies and convict cichlids had established breeding populations in waters in NW Wyoming, and guppies, mollies, swordtails, convict cichlids and a species of tilapia had established breeding populations in SE Idaho. Tiger barbs have been documented overwintering in Wyoming, but never established a breeding population.
Been quite a few years since I followed up on this, so don't know whatever became of these populations. I assumed the respective G&F departments would look at removin' 'em once they were discovered.
Anyways, I don't know a thing 'bout the lake yer sis caught the fish in and by no means am I sayin' it has a breeding population of convicts. An interesting bit of trivia and food for thought, though. And something to keep in mind for anyone who starts catchin' a lot of one species out of the same lake, regardless of how nonsensical the location seems.
WYite