My friend just got 3 oscars and put them in his 29 gallon tank. He says they are 3 inch, 4 inch, and a 4 1/2 inch. He said he will be upgrading to a 150 tank later on. I just want to make sure taht everythign will be alright. Will all three oscars be ok in a 150 gallon tank when they are full grown? Also, he said he wanted to feed them feeder guppies as treats, should he do that (i sent him the link about it) or is there any other treats for oscars.