I still believe in the smaller fish turn more money. Being that I work in the industry, perhaps I have a inside look compared to someone not in the industry. But a month doesn't go by that a discus/angel/bristlenose breeder doesn't stop into my store and try to undercut the guy before them.
Those breeders have themselves so saturated that Angels are $1.0-2.0 in price, same with bristlenose plecos. I have other customers who aren't in it for the money, who make more than these big time breeders do.
The problem with bristlenose plecos and angels/discus is the grow out time. It's insane compared to a lot of other in demand fish.
I have lots of customers who breed livebearers for us in their community tanks. All they do is feed it, and clean it once a month. Collect money every month.
For example one lady brings me 15-20 silver mollies every month that I buy for 75 cents each. She's not getting rich, but also it's just her 50 gallon community tank. With no places for fry to hide really and lots of predators to the babies. So she makes like $15 every month, without trying. She says "I'm just trying to get rid of these because I'm being overrun."
Here's the thing, I sell those mollies within a couple of weeks. Because they're locally bred and genetically healthy. Right now Florida keeps losing all it's stock from the freezes, making quality mollies on the wholesale lists scarce. On top of that, when they did have them in stock, since they're pond raised they were so genetically retarded you had large die off rates and diseases to cure before you could sell them.
If you were trying to make money off the silver mollies, simply take a 29g, fill it with hornwort and java moss, put in mollies, collect each month. Lets say you only produce $15 dollars worth.
To do angelfish, you'd need that 29 gallon for the breeders, another 29 to move parents once they lay eggs. And 3 55 gallon tanks for grow out. You'll average lets say on the high side of $2 each baby. The problem is your local store probably only sells lets say 50 angels a month. So you collect your $100.
15 dollars vs 100... Obviously you want the 100.
The problem is, you still have roughly 300+ angels sitting at home you're feeding. And to make this $100 you've used up 5 tanks from 29 g to 55g.
Now if you were to take those same tanks, and lets say fill it with, cherry shrimp, endler's livebearer, swordtails, mollies, and platies.
Cherry shrimp lets say 20 a month at $1
Endler's livebearer 10 pairs a month at $2 a pair
Swordtails 20 a month at $1
Mollies 20 a month at $1
Platies 20 a month at $1
You make the exact same money with this setup. $100 a month. However you also have diversified your portfolio. If another angel breeder comes around you're not stomped into the ground. Also the maintenance required to keep those 5 tanks going is MUCH less than the angelfish grow out tanks. You dont have to hatch live brine etc. You definitely could, and it would up your production on the livebearers etc.
The big "money makers" are already cornered usually in your area. They also have the most competition. You'll learn that the weekend breeder will often make the same "profit" as the guy breeding for a living. Sure the guy doing it as his main income has 200 tanks full of fry etc. But after operations costs etc, he's turning roughly the same profit as the guy with 10 tanks in his garage breeding "easy stuff"