I'm not an advocate of crowding fish nor the 1" per gallon rule. 20 1" chili rasboras would not be cramped in a 10 gallon; one 5 inch Oscar would be, to make an extreme example. It's all about mass and bioload, and keyholes provide more than average of both. a 30 long is 36" and you could probably have a group of 5 if 2 or fewer were males, in my estimation. Another issue with fish that provide parental care when spawning (such as cichlids) is that the rest would likely need to be moved out to prevent aggression come breeding time. Outside of Cyprochromis, not sure I've ever kept a cichlid species that didn't breed in my "community" tank -and those may have for all I know. Just something to think about. I honestly believe that you will find it more enjoyable to observe natural behaviors than keeping as many fish as will live in a tank anyway.