i had 14 uaru.f with 6 uaru.a no problems
the uaru.f were fine with my rays the uaru.a kept nipping at the rays disk
i also had a true parrot in the tank at the same time he was also fine with the uaru but he was fighting with a large tiger none stop
if you can get uaru.f go for it they were one of the best fish i ever kept
they are not as hard to keep as some people make out they just dont like the large water changes i was doing which is the only reason i sold them