[2020] Where can I find minnows? Wiki has no mention of them. Also, is this a bug? Because Bait Fishing is unlocked at Level 5 and yet it says I can fish at level 1.

The Ashdale tutorial is removed, but the Ashdale island has been accessible since its release.

You can get to Ashdale by talking to Gudrik the dwarf at Port Sarim docks. You can unlock a lodestone on the island to take you back to Ashdale more easily.

Fishing minnows requires bait, but there's a fisherman near the minnow spots who still provides bait - I think; it's been a while - if you need it.

IIRC minnows are also on crassian drop tables. So I think Ashdale is the only place you can get minnows.