"I was thinking the same thing, not only do you not know which species are which, looks like a recipe for rampant hybridization. I guess though the mutt fry would make good food for the Neo."
O_O I don't want my swordtail fry to get eaten by the cichlids! They max out at 2 inches; do you think they'd even be able to eat my swordtail babies?
As to how I keep them from hybridizing, well, that's kind of the point. I want
the Xiphophorus montezumae long tail trait partnered with the Xiphophorus hellerii tricolor spotted red, white, and black coloration. That's why they're in the same tank; I'm making a colorful, spotted montezumae-hellerii hybrid. That's why the lyretails are in there, too. They're beautiful, and I hope the line gets their deep red fin color and lyre shape. It's working, too. I've gotten some fry that are absolutely gorgeous that I'm super pleased with
By the way, that's how red swordtails were originally made, through hybridization and then backcrossing. The current "Xiphophorus hellerii" available to the hobby are only bright red because they have the Xiphophorus maculatus red modulator gene in them. The natural 'red' of the wild hellerii is much duller. The red maculatus gene, when expressed in hybrid offspring, produced a much redder fish. So people backcrossed to the hellerii shape (a sword on the tail, long body) and maculatus shape (short body, no sword) using hybrid fish with both hellerii and maculatus red modifier genes. There is no non-hybrid maculatus or hellerii that is that bright red. Some people weren't diligent with their backcrossing for shape, which is why you see those pet store short-sworded 'hellerii'.
But seriously, I don't see how the two inch Neolamprologus multifasciatus cichlids could possibly pose a threat to my swordtail fry, not when they're perfectly fine at escaping from their four to six inch parents. Out of any given fry batch, 95 to 100% of the fry born make it to reproductive age adulthood. (that's the point of the plants). Unless N. multifasciatus is a relentless fry eater?
What I don't know is whether the Neolamprologus multifasciatus will be able to not only comfortably survive, but also breed in my KH 6 water. I've never kept cichlids before, and I don't know if they have any odd quirks, like how goldfish enjoy to shred and dig up live plants. Or how mollies are small but so aggressive that I can't keep them in my tank because they beat every other fish up. Or how tetras refuse to spawn in my water because the pH is 8.3. I want every fish in my tank to be able to live comfortably and breed.
Update: Well, I guess I'll try it and see if they can live/breed in KH 6 water. Advice appreciated, of course, but I don't think anyone's looking at this topic anymore. *shrugs*