It only took about 3 years, although he continued to grow throughout from a 3" juvie, female about the same to reach 12" from a 1 " juvie.
If you check out fresh water collection site temps, you will see why the warmth is needed. one article below
Oh, Island in the Sun. The Dominican Republic by Alf Stalsberg ...
I also kept them separated with an egg crate divider until they bonded thru it.
I had started out with 12 individuals, and all died from bloat except the female, because I wasn't aware of the need for warm temp requirements (especially when young). Most of my cichlid tanks are kept in the mid 70s.
I believe (much like lizards such as iguanas) the warmth helps them process protein.
I did not however feed high protein foods.
They are omnivorous, and graze, and consume lots of algae in nature, so I chose a pellet high in spirulina (such as NLS algaemax) after delving into research of their nature habits.
above, their first non-separated encounter