he will be really big after 1.5 years and maybe slow down a bit! and I think he not gonna eat those cichlids in your pond, there is a member in this forum named TLKmDN that he have 2 over 40'' gator gar keeping in the same pond with oscar and they seem find for years !
He is eating so much its surprising. He will eat about 25% of a talipia fillet every night. still growing quick still and doesn't seam aggressive towards the smaller fish though im afraid that prob will change.