Generally you'd have to do one of those Central American species per tank because of the risk of crossbreeding and/or intra-species aggression, IMO. You could do a decent group of the cutteri and/or smaller/calmer species like nanoluteus, I think, but probably would only have one pair breeding at a time.
You might be able to mix a smaller Thorichthys with a pair of rainbow cichlids, for example (herotilapia multispinosa). I can't guarantee it will work though, especially long-term. You can also mix swordtails with Thorichthys, but need 1M:2F or 3F ratio otherwise the male kills off the female swordtails. But I'm not sure I'd do swordtails in a 24" tank, even though it's more like 2.5-3" corner to corner (not doing the math at the moment because my brain is tired).
