no two fish grow at the same rate but it's a good bet that you'll be looking at 18 - 24" as mentioned before... when owning one of these Amazon monster fish the best rule of thumb in pond construction is ... ASAP!!!!
I envy you!!! I was from the Phils. Feeders are so cheap over there compared to the US east coast. Do they still sell feeders by the bucket? They sell them here by the pic. SUCKS!!!!