The problem is fish don't read books and rarely care about what we want.

I thought a large harem would be nice and got 6 Bartlett's. Turns out 1 of them was always bullied -because it was a Dispar and much smaller than the Bartlett's. So I got some Dispars to keep the lone Dispar company leaving only 5 Bartlett's (plus a new family of Dispars).
Then a second male developed almost a year later in the Bartlett's family and they split off.
So rather than the large harem of Bartlett's I now have
1 Bartlett's Duo
1 Batlett's Trio
1 Dispar Trio

They're not Lyretails but even these smaller ones do pick on the littlest one it seems. Luckily so far the Bartlett's even with two males now have not been killing each other off though...