Yonder: The Cloud Catcher Chronicles

Yea winter was the key. I fished for gigalev all fall and didnt find a single one. The first day of winter I found 3 before noon.

Also for identifying the lucky fish, the bronze and rainbow have large gashes near their tail. The silver and golden have much smaller gashes.

This achievement is awful. Great guide, though! Had a ton of Gigalev spawn in the spot Kugare mentioned, but couldn’t figure out how to catch it; much smaller fish kept beating it to the hook no matter how much I moved around. Now it’s spring and I need to find a new spot to fish. Ugh.

Edit: I finally caught a Gigalev and finished this achievement (my last fish was the fulgur). I caught it in summer, in The Shivering Plains, on the coast just west of Inglenook. They were pretty consistently spawning between 8pm and 4am.

Had no issue with the Gigalev, I beat the story in Winter year 1 and caught 1 straight away in the sea by the end game area. I also caught 1 by the giant jellyfish in spring or summer the next year and a couple at the end game area in winter year 2.
The "lucky" rainbow fish was my white whale. Spent some time looking for it by the giant jellyfish whilst going back and forth to the vendor in Mocha bay with no luck. Eventually went back to the end game area as a steam guide says thats the best area for it, it took over an hour before I finally got it and can be done with this game. (Cats were a pain, but at least they were easy to find, this was just a tedious grind)

The yang fish is in the river in Dapplewood Forest between Arbre Ridge and the Sage Stone, it is one of the fat big silhouette fish, and moves very slowly compared to the other ones of that size. Available between 5-7 AM. The Yin fish is the same; same place same silhouette, but at 5-7 PM.

Also, you can just buy fish in mocha bay and it counts toward the achievement. Just head to mocha bay and check every once in a while for the rarer ones, if you are having trouble finding them by fishing. The only difference is the record will still say "???". I can confirm that it works to get the achievement because i bought the queen, prince & rainbow and it popped when i spammed fishing until i got the last item i hadn't got which was a boot. If you have been working on your farm, potatos, herbs, berries are all worth alot and can get you the fish from the shop easily.

The hilarious thing is, im having a hard time finding the Boot is the last item i have to fish for. You can't buy it if you happen to be "unlucky" like me and not find one.