Just wait till it gets drop eye and tell him off, then maybe he will learn about some thing called research before he gets a fish. I have friends exactly like who you are describing. If there like some of my friends there not going to listen to anything you say until they face check and run into a problem. It's his fish and he can do what he wants with his fish, it is a shame to see such a fish in the hands of such a bad owner but eh what can you do. He'll learn the hardway. If the fish is about 3.5 inches I estimate it will be good for over 6 months. It depends tho. My friend has gotten his jar the same time as me at 6 inches and mines a good 10-11 inches and his is still six inches.... and it has been about 3 months. His water quality is so poor... And even leaves a fh with no heater lmfao.