You’re right about needed extra false amanos shrimp to try breeding them.
The way I breed Amano shrimp by generation, I may run out of berries Amano shrimp to keep breeding unless I can find a way to increase the survival rate. F1 and F2 are not much different in berries size compared with wild caught F0 shrimp. From F3 on, the Amano shrimp getting smaller and hatch out larvae getting less. Unless they are getting easier to breed, I may hit the dead end.