Recent aggression in existing pair of clowns

LookItsAdam · Dec 14, 2020

I had a lone ocellaris clown fish in my tank for about a year before getting a second clown to pair with it. The new clown I got was significantly smaller, about 1/3 the size of my existing clown. They seemed to pair up almost immediately with only some minimal aggression in the first day or two. They are always swimming together, and seem to prefer hosting my wave maker together instead of the anemone, which is fine. It's been about 5 months and everything has been great, until this week.

I've noticed the larger clown getting a lot more aggressive to the smaller clown (who has now grown to about half the size of the larger one). The larger one will chase the smaller one away from their spot by the wave maker, and the smaller one has been sulking in the corner by itself. Is this normal? Could they just be figuring out their genders now?

Any advice would be welcome!

ichthyogeek · Dec 17, 2020

@OrionN ? I defer to your anemonefish expertise here.

OrionN · Dec 17, 2020

When clownfish mature they become a little more aggressive. I am sure your larger clownfish is turning female and will show tendency to become dominant. Ocellaris are pretty mild and the smaller one will be fine. Once he accepted the dominant of the other clown, they will be together again. This is what happen when we raise a pair from small. They were fine for a while then start to fight for a time.
If your fish are hybrid, they can have mixed/unclear signals to each other result in the smaller clown get beat up more than normal. If they are pure breed (of the same breed), there will not be any problem.