From what I've read 2ft to 30" in rare cases in home aquaria, they're pretty quick growers first year but slow waaaaaay down after that. I really enjoy mine, now that the pearsei isn't king konging his way around the tank the gar actually hangs around the front glass when I'm around, and is always waiting for those first few nuggets of food when I drop it in so he can snap it up. Really entertaining fish, and I can't possibly oversell how compatible he is with the polys, never flips out, never nips at anyone, just chill as can be