Salmon spawn in cave lakes (local water levels)

Put the summary of the bug you're having here

What I expected to happen was...:
Fish shouldn't spawn in caves as:

1. they have no way of getting there

2. IRL only certain specialised fish live in cave water bodies

What actually happened was...:
2 salmon were in a cave lake at y =-35, note that they weren't moving either.

Steps to Reproduce:
1. Look around cave lakes until you find some