I would say it depends on what you understand as naturalistic setup.
As long as there is some hiding space for eggs and fry and you provide the right water conditions they will constantly reproduce.
It also depends on the species.
As a kid I had a 240 liter tank (considered quite large at that time) with 10-12 Odessa barbs (P. padamya), a pair of Hemichromis, some plecos and a raphael catfish. Half of the tank was covered in a thick layer of java moss.
Twice a year I could bring around 25 barbs to my LFS. I did not understand at that time, how rare they where and never got any fry out of the tank. I just brought what survived in the tank.
I was quite disapointed when I finally could bring them 50 Hemichromis which I raised in a separate tank and they paid way less than for the barbs.
I think without the other fish and a bit more care it could have been way more. The barbs spawned after every water change as long as I had them. So they can compete with live bearers when given the right conditions. Which is one the reasons why Pseudorasbora parva is banned in the whole EU.