The bottom line is always species by species. It's just logic that the fish most available from the farms are generally the easiest to breed. They like easy, and don't want to deal with labour expensive special set ups to mass produce fish. So when we get those fish home, we have to be more interested than directly skilled. Those fish are relatively easily coaxed to produce.
That doesn't mean breeding them isn't an accomplishment, because a fish farm is located jn the tropics with water that corresponds to the needs of the fish they specialize in. We have to be willing to learn and do a little work to accomplish what's easy for the pros.
The next level up fish don't have 3000 babies in one shot, or aren't easy to breed. They're a different game to figure out the rules of. They're the ones we have to condition pairs for, prepare very thought out tanks for, etc. To me, they're the fun ones.
As far as I can see, the Pristella maxillaris I set up to lay eggs did so yesterday during the day. The 2 females looked 'depleted'. I'll remove the adults today and be very disappointed if I don't see fry in a couple of days. I expect that will have worked. They're common, pet shop/fish farm species, and I really like them. But they are less of a challenge, in general.
The Neolebias trewevasae I set up a couple of days before also appeared to have spawned. They too were conditioned, in exactly the same way. I saw what appeared to be a small group of fry last evening. I couldn't be 100% sure as they moved quickly and I want to keep them dark. That's a whole other feeling. There, I expected failure and it's kind of intriguing that I might be raising another generation from these wild caught fish. If that has worked, I'll buy myself a coffee to celebrate.
I'm breeding both fish to raise small numbers, and have a larger shoal/group to enjoy in my tanks. If I get more than I want, I can find local people who would like to keep them. That's what fish clubs are for.
So with challenging fish, you go through extra steps. You condition them specifically for breeding. I can have very healthy fish fed flake and pellets. Many of them will not produce eggs on that diet. So special diets can be needed.
Special tanks too. Sometimes, special water conditions. I'm peat filtering one of my Cichlids and am down to 30 tds in their tank, from 65. Will it work? It entertains me to find out. I put my Bathyaethiops greeni (an African/Congo tetra) in a breeding tank with screening to protect falling eggs, and mops to catch aggs, but haven't seen fry. They could be there. A farm would want 1000, but I'd be happy with 10 or 15 for my purposes. Today, I'll carefully remove the mops and ground cover, to see if I can spot any movement. If not, I'll figure out what to adjust, and simply try again.
I like watching how little slivers of life turn into the beautiful fish we admire in each other's tanks. Watching how an angelfish, which starts shaped like any fish develops those weird adult fins, or how colours set in on a young killifish or tetra is fun for a nerd like me. That's at the heart of why I condition fish for breeding.