I had a pair.. when obtained the male was ~9" TL female was 6.5-7" TL. For quarantine they were in a divided 30 gallon (36"), layed eggs on the divider.
From there they went into a 125, where the male was always the biggest fish in the tank, and captured about 3' of the tank as his territory, along with the female. Tankmates were an 8" nicaraguense, and a mix of other fish - Crenicichla sp 'venezuela' up to 12-14", Petenia splendida, managuense (small), some female bifasciatum up to about 6", pair of motags, a few texas cichlids and green terrors- lots of turnover / churn in this tank.
Anyway, the male always dominated all of those fish until the pair was sold about 18 months later, at that time the male was over 14", very bland though, basically very light gray with a red tail, and the female had more of a blue sheen over much darker gray.
They were typical Vieja- begged for food, enjoyed tons of pond snails, and any other food offered, and able to stand their own with just about anything. They may have small mouths but they hit hard and when they get a good bite in on the flank those other fish pay attention.
I'd avoid much larger / stronger species except in a very large or densely populated tank- Amphilophus and Parachromis are just going to depend on individual's personalities and a lot of other factors whether the mix is going to work.