What size tank and what other fish do you have? Lone angels are fine on their own, I have tried adding a female with my lone male, well I bought 2 and he killed both of them overnight . They can be funny devils, you might add a female and he will be perfectly happy and they pair up, or he could be like mine and because its "his tank", kill any other angels you try and add. Its difficult to say yes or no, the only thing is to try a female if you have another tank available to move her into should he get aggressive, if you dont have another tank then best leave him on his own. Or if your tank is big enough get a another 5 angels so you have a group and you would get a pair that way. Hope this helps
65 litre at min I have 1 angel fish 4 tiger barbs 2 dwaf gourami 1 red tail shark 1 small synadotis catfish but I am looking now to get a new tank thinking jewel rio 300 cheers