yes, breeding most freshwater fish are fairly easy (the livebearers, the SA cichlids, the Afr. cichlids) and feeding the fry is simple enough as you either use BBS or crushed flake food.
Clownfish and seahorses require you grow greenwater (algae) and the feed small single cell animals called rotifers. Read through some of the sticky threads up top on this forum. It can be done and having a background in freshwater fish will help as the clowns spawn just like the SA cichlids (on a flower pot).