I've been trying to introduce my new male rat to my older male rat. I put them in the bathtub and they do fine. They sit right next to each other without fighting. So, I decided to put them in a cage together. I cleaned it so that there were no scents left behind. Again, they do fine for hours. But then they'll have one quick fight and the new rat goes into hiding and wont come out. I'm not sure if I should leave him in the cage with the older rat or take him back out. I'm worried he won't come out and eat/drink because he's afraid of the older rat.