I've read they like faster moving waters. They are also walkers/climbers. I remember when i had one, it would crawl instead of flop around when out of water.
Looks like there is a permit to legally
collect from streams for aquarium use: https://dlnr.ehawaii.gov/cmls-public...F-81C938E7C288
And under term #9, O'opu cannot be taken.