Reds are generally known for being docile. Where have you been reading that they are aggressive? Is it referring to one particular animal or reds as a whole?

The tegu usually known for bad behavior is the Colombian tegu.

With reds, you have to feed them a good portion of fruit in their diet - they can develop shedding problems if you don't. And they can take a bit more heat in their basking area - maybe 120 degrees. Cool end 80 - 85.

Reds are great animals.

Bill