Aggressive adult male rat intros

Question
hi again! i rescued a 5 months old rat that was taken into a pet store with two others and ended up being left alone. (my current rat was also recently left alone, his 1) i introduced them in the bath tub and all seemed to be going really well but the day after the new rat became very scared and wouldn't let my old rat near him. he lets him stay for a while and then starts hitting him in the face and making loud squicking sounds. new rat then runs, old rat runs after him and they get hold of eachother and role round in a ball fighting. it seems quite vicious although i don't think either have bitten and drawn blood. is it normal for them to be so hardcore about it?! ive been breaking it up or the new rat runs to me for safety but im not sure i should be? is it maybe because they were both alpha males of their original groups? sorry for such a long question! im just wondering if im doing the right thing pushing them together? ive been introducing them everyday for about a week, thanks

Answer
Dear Rachel,

One or both need to be neutered. Probably both, or the still-aggressive intact one will still attack the other. The way they are now, one is likely to end up dead or severely wounded.

It is great that you knew your guy needed a friend, and great that you took this lonely guy. Neutering is an expense, but it will make happy rats out of them.

Best of luck and good health to them,

Squeaks

Natasha