I know they say don't hand feed your tegu, but he always sees me throw the rat in his cage. Now every time I open his cage he comes running at me like he is going to bite. He didn't used to be so aggressive towards me. Now I can't even pick him up without him hissing (or taking deep breaths). What do I need to do to stop having him attack me, and so I can pick him up again. He is about 2 1/2 feet. 

show him who the boss is. handle him more so he doesnt think every time you open his cage hes getting food. also you can take him out and feed him in the tub or some were besides his cage, that should help alot.

my advice is to place his food in before you turn on the light and let him feed without you around for a few weeks. It is a good idea to feed tegus in feeding bins also. You just need to let the tegu know thats its handling time not feeding time I would use a old shirt to gently pet the tegu and handle. lets the tegu know its not being fed. good luck

DO NOT FEED HIM IN HIS CAGE. this is your first mistake. i have a colombian tegu and with these being aggressive already i make sure to have his food on the table and then bring him to it. not only does this help tame cage aggression but also allows him to get used to me handling him. and do not hand feed. have u seen the size of a full grown tegus teeth...might as well be a gator

Hey,

I have a trick I use to keep them from becoming food aggressive! take him out to soak him and while he is soaking, pu his food in his enclosure..that way he will learn that when you take him out and give him some attention, his food will be there when he gets back! You would be surprised at how fast they learn this, and look forward to you taking them out..I have experimented and found that a happy Tegu is one who has everything in his enclosure, including food..