saltwater fish possess a series of difficult questions.
The two main problems w/ Sw fish are planktonic fry (many fish have plankton sized fry which live in/amongst plankton while they grow), 2)- many SW fish have incrediblely tiny fry which require smaller nutrionally complete first foods, and we hobbyists can't figure out what these tiny fry eat or how to grow the first foods
These are two main problems
next some smaller problems
unlike freshwater fish, many Sw fish have huge adult animals, so obviously housing can be a problem.
Next keeping male/female fish in small tanks often leads to aggression, yet another problem.
So right now today, the hobby is pretty much limited to breeding small fish whih have tiny ranges and, importantly, have adult supervision of their fry.
Clownfish, dotty back, banggai cardinals, seahorses, gobies are all comonly breed fish and if you look at all the commonalities you'll understand why
frank
