So I have had a clown alone in my tank for a long time a few years. I want to add another but I am worried about adding two females. What do you guys think?
There really isn’t a way to tell unless the fish is large and will likely be a female. Your best bet is to purchase a small juvenile clown and let them change.
I would get a tiny 1" or so clownfish of the same species from your LFS and then keep it in a social acclimation box for a few days after quarantine before letting it loose.
If she’s a big girl I’d look for something a little bigger than 1” just so long as it’s still an unsexed juvenile. Sometimes the females can be a bit rough on the real little guys. Also if she doesn’t play nice you can put her in the acclimation box, kind of a sort of time out so that the new guy can get accustomed to the new tank without being overly hassled. It’s her tank right now so she might be a bit territorial, removing her to the acclimation box will help with that. Just make sure you keep a close eye on them and be ready to remove one or the other if it gets too bad. What kind of clown?
If you purchase from a Breeders you’ll be more likely to get an unsexed juvenile since it will be likely be housed with its clutch mates and not given a chance to establish dominance. The same might be said for an lfs depending on where they get their stock from. Just make sure you don’t get the largest clown and you should be good.