on how you interpret it:

If you mean which fish has the greatest latitudinal range only considering that range in the US (occupies two points, both points being in the US, which are on lines of latitude furthest from each other) then my first guess was northern pike. They are in every reach of Alaska (71.05N) and I’ve personally caught them in Ashurst Lake in Arizona. (35.01N)

That’s about a 36 degree range.

Drum would be from northern edge of Minnesota (49.31 N) all the way down to the tip of Texas (25.96 N). But limited to the contiguous states.

That’s about a 23 degree range. (I know channel cats and bullhead and probably many others occupy all of that same range too.)
So the winner I think is going to have to be in Alaska too. Like the pike.

But if you mean furthest *world-wide* latitudinal separation of any freshwater fish that also includes the US, then the rainbow trout lives in both Alaska/Kamchatka and New Zealand’s South Island or Tierra del Fuego at southern tip of South America. Browns are similar but northern edge of Scandinavia. That’s pretty much as far apart as you can be in fresh water on Earth. We’re talking around 125 degrees of separation! Not native range, though, and not contiguous.

So maybe drum have the largest *native* *world-wide* latitudinal range that also includes the US? International range seems to be about (56.89 N to 14.97 N) ~42 degrees (Guatemala to Hudson Bay)

That last definition would be hard to test off the top of my head though. Lots of guess and check, so I’ll assume that’s what you meant and that you’re right. Because my tiredness has finally come to overtake my curiosity and I can sleep.

Thanks for the bedtime diversion project 🙏🏻