Three-year-old clowns are similar size.

[dolfanjack]

I have two Ocellaris clownfish in a twenty long. I have had them over three years now. When I got them, one had been in the tank for several months (had two one died). When I added the second fish it was half the size of the first, initially. They got along great and still do. They must be a pair, but the second fish is now the same size as the first. Is this out of the ordinary? Curious, Thanks, Jack

 

[Peace River]

Normally dominance and aggression sort things out in the clownfish world and the dominant fish becomes the female and grows larger and the less dominant fish is the male and remains smaller. Normally the question is related to the level of aggression as that dominance occurs. That is the "normal" pattern, but it is possible for clownfish to coexist without the dominance and without the transitions.

 

[Timfish]

Unusual but not what I'd consider a problem yet. Females usually will grow quite a bit once they start laying. What would be atypical is if they don't start reproducing in the next year.