I had never found a Mountain cave that had an unfrozen, Tetra filled lake before.

Until this morning...

I was scouting Moder's altar getting ready for the fight and found a cave nearby so I decided to duck in for a quick look.

As soon as I broke down the ice wall at the entrance I saw a small pool just to the right and around it, beached, were several Tetra. More of the fish swam happily about in the pool itself.

Sometimes RNG can be on your side. No golems, no deep cave clearing, (but also no fishing pole and sad skeleton) just kamikaze Tetra waiting for me at the door.