When I was down to just one male and one female Bristle before one of them died, the final spawn was over 100 eggs and most of them were viable.
I work with Hypancsitrus now and having sold three of my 7 breeding groups last year and I still have over 200 assorted size offspring. The nl;y produce about 15 eggs per spawn with most being viable. 20 is a big deal and a dozen is not that rare either.
I never set out to spawn my fish. It just turns out my well water apparently contain a natural aphrodiseac for softer water fish. I have anegel, discus, 3 different danio species, 3 small rainbow species, rosy barbs, bristlenose, one farlowella species, P. nicholsi, sterbai, aeneus, and a couple more corys, P, compta, 5 species of Hypancistrus all spawn. And only 10 of them were species I was hoping and trying to get to spawn.
A lot of being successful at spawning fish depends on the parameters of your water. Pretty much all fish want to spawn. So our job is not to do things that might discourage or prevent this. After that it is diet. We control it and for most fish it need to be good quality and the right food. After water params diet is likely the most important factor for getting spawns for fish.
Farlowella vitatta dad keeping the eggs clean. This was my high tech CO2 added planted tank. I just got 3 farlos because they look so neat and they eat algae. The spawns were a bonus.
Spawn something you like and that is happy to be in your water params. Feed them a high quality diet and give them the proper living conditions and you can watch them multiply