I watched that clown vid. I saw no breeding clowns, I saw no fry I saw no eggs. I have some big clowns 10+ in. TL. They eat anything. They shred the Repashy Igapo fruit mix. I throw in chunks too big for them to simply swallow whole and they mange to eat it, no problem.
There is usually a very good reason certain fish have not been bred in tanks and likely never will be. Those rare almost impossible-to-beed-in-tanks are most likely to stay that way.
So what is your goal in breeding rare fish, money, glory or both? There are plenty of pricey fish one might breed in tanks. Often the biggest problem if finding the fish available. A perfect example used to be zebra plecos. Illegal to remove from Brazil and harder to find. But the illegal trade fixed that for a while. Now it is almost impossible to find wild caught zebras. However, there are enough folks breeding them in tanks and on a few quality farms that you can still find them without too much difficulty. However, the prices still remain high.
On the other hand something like an L173 is hard to find and the prices are high. Fortunately, at least in my water, most of the Hypancistrus plecos seem to spawn. And that explains the other consideration. One usually gets the best results working with fish that are at home in our tap water.
On observation- I believe most fish we keep in tanks want to spawn. The reality is we do not get them to spawn. Our first job is to provide the proper conditions- i.e. prroper sized tank, proper water parameters, and proper aquascape. After that the one thing we can control is what we feed. As far as I am concerned this is usually the most important thing we do- feed the right foods. In the end, our fish will usually spawn as long as we are not doing things to discourage or prevent it. Also, most require a species tanks if we want to maximize survival for offspring. many can require a separate growout tank to be safe.
Yes there are a bunch of fish who need very special parameters/conditions/foods. Some may need ponds rather than tanks because they are big. But these are not the ones most folks breed unless they have lots of space and specialized equipment etc.
If all you want is glory, then go for the clown loach type fish nobody has managed despite years of tying. Just be prepared to fail. If you are interested in making some level of profit, go for spawnable but hard to find fish which grow slowly and have small spawn. Zebras are pricey because they take a while to reach spawning size, they have a small clutch of eggs.
A lot of your choice may come down to moneny. How big a tank will you need for spawning and then for growout. How much to the fish cost. Will you get youngersters and grow them or will you lookfor adult fish ready to spawn or even proven breeders? It Took me a while to work up to it, but my most expensive breeding fish cost me $1,000 each. If you work with big fish, shipping can become a challenge.
Here is an idea- Altum angels. They have been breed, but by very, very few folks. I keep them and have no illusions about getting them to spawn. I do not have the skills.
