Profitable fish to breed?

I would personally choose bettas. They are cool and interesting fish and are interesting to breed. I love watching them build bubble nests and fight! As for profit I am guessing if you were to buy some high quality fish you could probably make some nice profit.

Cichlids are easy to raise from fry - and good pairs pump out fry like nothing else - and you get a LOT of fry in a very short period of time. The trick will be to actually build a customer base from the very beginning. Talk to your local pet stores FIRST, and make sure they will take them.
Depending on your level of skill; you could also go with something that is very slow to breed, but profitable, such as stingrays, or even some marine fish, or some of the more rare cichlids.

People often suggest livebearers, but the profit turnout seems to be very low, since it takes a lot, to get a marketable amount of fry.

Also - to state the obvious - we don't even know what you have, to start with, equipment wise.

Keep us updated!

Bettas are a nice choice - but the fry are very hard to raise. Again - not knowing what your skill set is comes into play here.

+1 if you go with bettas remember they are not the easiest fish to breed, as fwprawn said the fry can be hard to raise.

Down here L numbers seem to do pretty good but I hear they can be a bit difficult to get going.

Anglefish are popular and easy to breed. Therefore they would be my choice.

A few fish I've bred in the past that I sold and made nice trades for fish to fish stores. Jack Dempsey sold $1.00- 1.50ea about 1000+ fry, dovii's sold $1.50-3.00ea 1000+ fry, Angel fish $1.00-1.50ea 1000+ fry, Green Terror $1.50ea 500+ fry. All these fish I raised to 1-3" size the bigger you can grow them the more you can get but you need tank space and you start spending more on food.