Note: I am not endorsing this as the best/most healthy/whatever method for breeding fish. This is the way that the dude I know at a fish farm uses. They're a commercial breeder and ship to a number of the area pond builders, Petcos and local fish stores. They currently breed Africans, South Americans, Goldfish, Koi and some other coldwater fish (more for pond stocking tho like channel cats and bass) and are going to be getting into tropicals this summer supposedly. They ship something like 2000+ fish a week not counting pickups. The guy I know is mostly in charge of the coldwater end of things, so he said he may be forgetting something, but that's pretty much the basics of how it's set up.

Also, the owner doesn't allow pictures inside, and I'm also forbidden from naming the place, since on the (extremely outside) chance that they see and then figure out who posted things online, my friend could get fired.

Anyway, here ya go.

For African Cichlids:
4, up to 4 to 6 inch (depends on species) 3 females, 1 male are put in a 20g long.

In the tank is an number of pieces of 4" pvc pipe, some capped some not, glued together in an x pattern. - are open pipes ] are caps. (ignore the dots the forum was ignoring my extra spaces to make it look like an x)

-] [-
..-
-] [-

There is a sponge filter with a large dense plant in it at the top of the x. The plant varies depending on stock at hand and fish species since some are worse to plants than others. The tanks are all also drilled, for slow filtration and ease of water changes on a sump system. Each system is 10 tanks, with an additional 150 to 200g basin. (They got shipped 150s by mistake once is the only reason on the variance on that part)

According to him, the plants and pipes give enough hiding spaces that they usually don't have agression problems from the males. Some species are worse than others (and he can't remember which exactly) and at times they will have to pull an overly aggressive male, but that isn't all that often.

Once they outgrow the 20s, they are moved to 40s same setup, males are sometimes swapped around and the process begins again.

Fry go to grow out tubs, mostly livestock tubs since they are thick walled and retain heat better. Again depending on species, at 1" to 2" they are shipped out to stores.

Problem fish, either deformities that weren't caught in the culling stage or overly aggressive fish are put into "sucks to be you" tubs, (my naming is starting to stick up there, mwahahaha) to either become food for other larger fish (or my turtles), or in some cases for me to find homes for, as I know some people who will take any fish of a certain type regardless of missing an eye or having some other weirdness. (My mom suffers from multiple pond syndrome for example and will take anything that can survive the winter outside)

He's never dealt with the South American ones they're in a different area, so he's not sure what they're doing. He assumes it's something very similar. He does know they are breeding Oscars, Jack Dempseys, Midas, Angels and a few others that he couldn't remember. He's is however excited about starting tropicals because he really wants to breed Pacus after seeing my big boys.

Interesting, thanks for sharing!