Nice pickup! They differ in growth rates. Depends genes, on what you feed- etc. Feed a more varied diet for best growth.
I feed:
Pet store bought:
Hiakri Sinking carnivore pellets, Hikar Marine-A sinking pellets, Plankton sinking pellets,
Algae tablets, Tetramin variety pellets, Omega One Shrimps pellets, HBH Cichlid Attack pellets
Frozen: Bloodworms, Beefheart, Ocean one marine, Brine shrimp, Mysis shrimp, Squid, Silverside, Krill
Raw: Shrimp,Chicken, Hamburger(rarely) Anchovies,
Live: Ghost shrimp, earthworms, Guppies, Mollies & their fry
Store bought: Frozen shrimp, Tuna( once in awhile)