Jolly Fisherman wrote:

Discus is where both money & broad interest seems to be for
freshwater. My next experiments hopefully will be with apistos (wish
me luck). This is all about fun and challenge for me. I don't need
or expect another business from it.

The professional breeders I have traded with were mostly in Discus
breeding, although these same breeders also bred angels and Afrcan
cichlids. I assume they were making money at this (never asked), but
they are still in this same location in So. El Monte, CA today.
My main experience was the same as Koi-Lo, I have bred shubunkins and
Koi, but I have made money with the Koi, and a did not give that much
special attention or additional care to them other than a good
environment and some powdered Spirulina Flake.
I also have bred Mbuna and Tanganyika cichlids. As with the Koi, I
think the Tanganyika at least paid for themselves. And of coarse I have
had livebearers do their thing, but that hardly counts as breeding for
me (at least the way I have done this, as I do not want to insult
professional guppy beeders would breed magnificant strains of guppies).
What it come down to in my view is a qualtiy environment, which is what
about everyone here has basically alluded to. Everytime I have been
successful (often by accident) the environment was in excellent
condition and this included anemones, starfish and similar in my marine
tanks.

Carl.
http://www.americanaquariumproducts.com/ClearPond.html