Hi.
This Endli was donated to me, as is.
So It's growth rate I don't know.
The only info I have is that it is wild and was a complete bully in it's last home, though very tame in my tank.
I am feeding it on Massivore, shrimp and fish cuts. It has a huuuge appetite!
Of my other Endlicheris my biggest is 18" and that has taken a few years to get there.