Suspected Fungal Infection and one poor option for quarantine

I just received an online order from a store that I'd never purchased from before as they had an angel fish I couldn't source locally or from other online stores I usually buy from. I'm currently floating the bag in my tank (after rinsing the outside first) and I've noticed that the fish seems to have a fungal infection on all of it's fins. I don't want to release it into the tank with my disease free fish but the only other option I have is a 38L tank 2 weeks into it's cycle that has no filter (it stopped working a week ago and I'm waiting on a replacement that was meant to be here by today but hasn't arrived). My only option is the cycling tank but I don't want to jeopardise the new angel's health anymore than it is. Any ideas on what I should do? Thanks