Above poster's idea is good, with fancy betas but I think you have more tanks than youd need. Cons will breed like crazy, you'll be filled to the brim with them and no lfs is desperately seeking em trust me, so bad idea there.
With the size of tanks you have you could do some small angels (I mean the extra small ones) most barbs, danios, any livebearing fish.
You may never realize a profit but if you do it's going to be with common fish that lots of people want ie. those I mentioned just before. Id go with some guppies, pick a nice variety you can get both males and females of and line breed for a particular desirable trait. LFS always have multiple guppy tanks and guppies always sell so you should be able to move them. Platies and swordtails are also a good bet, even some mollies.
If you happen upon some really spectacular specimens of a particular common breed, for example zebra danios (unlikely with this breed lol) grab them and breed them. The lfs will always carry that species but if you can supply a constant stream of nicer looking ones they might make you the primary supplier. I have some red glass rosy barbs like this. We see them in the stores often but the store fish are drab and misshapen compared to ours and as a result we have lfs after ours now. Ironically we purchased the fish from one of those lfs and they looked just as good when in store and the manager has a huge fish room he breeds in, and hes bred rosy barbs before but he didnt snap any of those up so hes left with the poorer stock coming in from farms. If there's a few lfs around take a look at them all and mark the best stuff, look it up on the net and see if you can breed them with your setups, if so go back and grab em.
The other route to go for money making is to breed rare and exotic fish that few people can get their hands on. Problem is getting the initial fish, replicating their breeding environments and then finding enough people to offload these expensive suckers too.
Discus are probably one of the best species to go with Id imagine, as they sell for quite a bit, are in demand and lfs can carry hundreds of them at a time (small ones anyways) but your tanks are too small and youd need to buy many good specimens and then hope for a pair.
IMO best bet is small cheap fish that are highly desirable and easy to breed in your setups. Make sure you use at least one tank just to look at though, otherwise it can get to feeling like a job

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