A few days ago my Yoda passed away-we didn't expect him to die so quickly at only a year old. This leaves Chewy needing a companion but I have so much to think about that I need advice. Recently Chewy has become quite aggressive; I think it's just a build up of testosterone but Yoda's illness and death most likely have contributed to his stress. He bit my dad, causing him to bleed and has bitten me quite a lot even though it hasn't drawn blood. I'm being careful around him but he would occasionally start nipping quite hard on my hands or sleeves in a pulling motion. His fur piloerects, he takes audible sharp angry intakes of breath and become defensive when I try to pick him up during playtime. He needs to be neutered and I called about 20 vets around my area about vets who have castrated rats before and how much it costs. The cheapest are at around £70 which is quite expensive although I do understand all the sedation and medication costs. Also he has a little bit of a sniffle which I'm treating and he's 550g which both might increase risk of the surgery. Could this aggression be a faze or something that needs to be fixed? Then, his pawtner. Firstly I don't think he'll get along well with other rats if he's being aggressive towards me. Secondly I prefer not to get more rats because of the heartbreak and stress I've been through with these guys (however amazing they are), but I know I have to because Chewy's only a year old and absolutely could not live alone for potentially 1-2 more years. But to prevent an endless cycle of ratties, I'm planning on adopting a single rat. The problem is, not many rescues near me have rats and I've been on websites where people advertise pets they can no longer care for, but they are mostly babies. Maybe I could get two more older rats but again, they're hard to find. My best hope is to keep on looking, but I don't know how long it's going to take for us to get lucky and I also don't know if I should or could get Chewy castrated. A lot's on my mind. What should I do?