Replacing One of a Pair

[Crusinjimbo]

I lost one of my OC clowns after the hurricane last year. Paired for 7 years. The survivor is heathy and eating and about 3+ inches in length. He is the only fish in a 13.5G tank that maintains excellent water quality (NO3/PO4 almost undetectable) via a hybrid refugium/scrubber. Opinions on adding a partner either, another OC or fish, would be appreciated.
Jimbo

 

[davocean]

Get a clown no bigger than an inch and a quarter to assure it's still male, float in an acclimation box next to existing, hours, day.
Observe existing.
if it was the larger of your two, it is female, if not, it will become the female

 

[Crusinjimbo]

Thanks and the survivor was twice as large as the other.
I’ll give it a go.