I'm a water change guy. Most fish can survive in concentrated wastewater conditions. The dry season in many tropical regions creates pools, cut off by sandbars and exposed river bottom. They gradually evaporate, causing the fish in them to hunker down and wait for rain. They exist. Systems slow down, breeding stops, etc. When the rains come, they burst out and live again.
I'm not sure I want to watch my fish go into that murky stage in life.
I used to have wild caught Mexican mollies that a friend collected from such a pool, a very shallow one. She went back the next day and the local birds were scavenging the ones she didn't catch. The pool was wet mud.
I grew up in the 'don't do water changes' era, and for the first 15 years of my 55 years in the hobby, I changed no water. If I compare lifespans, vitality and breeding, then and now, I won't double back. I'll never see that dwarf variatus strain I thought I had though. When I started water changing, they returned to normal size in a generation...
If I lived in a water shortage region, I'm not sure what I'd do. Probably move! But in all seriousness, I would probably reduce my choices to swamp species.