I don't know if the fact that you are dealing with L025 matters, but in general, I think your decision was good. Assuming you quarantine the new fish when it arrives before putting it with your other L025s, and assuming you get a new fish that is about the same size and sexual maturity as your other L025s, that may trigger the male's interest. I've used that same strategy with other plecos, with corys, and with some cichlids. I suspect that the success in fish is similar to what has been observed in some mammals, a phenomenon called the "Coolidge Effect:"
Wikipedia wrote:In biology and psychology, the Coolidge effect is a phenomenon seen in mammalian species whereby males (and to a lesser extent females) exhibit renewed sexual interest if introduced to new receptive sexual partners, even after cessation of sex with prior but still available sexual partners.
The emphasis in the mammalian effect is that the male has already mated with the first female and has lost interest, but I suspect the same rule applies to males which never show any interest in a particular female from the beginning.
In my original group of four clown plecos (2 males, 2 females), the males never tried to mate with the females I had until after I introduced two new females (and one more male by coincidence). Ever since, they haven't stopped spawning.
Regarding your fish, my only other thought is make sure you have enough caves and hiding places for the three fish to get away from each other, in case they don't get along.
Good luck, Eric
