Freshwater- Thalassophryne amazonica - is the most available FW. Not sure how many species are freshwater but i think Daector quadrizonatus and D. gerringi is too. They have IMO nicer markers, and have slightly larger eyes, but I think it would be harder to find them.
The first species has def. been captive bred before.
They need a substrate they can bury in they like to hide so only basically there eyes are protruding from the substrate so it has to be kinda deep. They do well with a reasonable flow and a slightly acidic pH. They can be fussy feeders only excepting live foods and only when they swim over them, but i think they accept target fed prawns too. They are found all along the amazon and tributaries and these are the true prehistoric monster fish!