Hey! I recently adopted a 7-month old female, Hana, who has been living alone up until this point. After quarantining I have been slowly introducing her to my two other girls Ame and Yuki who are just over a year old. I started with having the cages about 6 inches apart and swapping items back and forth every day so the girls could smell and see each other. After 4 or 5 days of this I introduced them in the bathtub, which went well with my resident girls pretty much ignoring Hana the whole time. The second time there was some aggression: - after a couple of minutes Hana and Yuki were facing off between each other with puffed up fur and arched backs. They then reared up on their hind legs and 'boxed' before sort of exploding into a rat scuffle. I separated them immediately but am not sure if this is something I need to let them sort out as I have heard elsewhere you only need to intervene if there's blood. Is this true? -Hana also puffed up and was backing her butt into Ame, my other resident rat. I heard this was a bad sign of aggression but Ame didn't respond back aggressively. Do I intervene in cases like this? I want to make sure I do intros right and am just overwhelmed with knowing what is good and bad behaviour. I don't want this intro to fail. Any advice is very much appreciated!