Clownfish behavior change

Bamzam

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I have a 4 year old tank 12g long with 2 clowns as the only fish. One has been there all 4 years and the other for about 3.5 years. Just today, the bigger one all of a sudden got really aggressive and is constantly chasing/attacking the smaller one everywhere. There are a few events that have happened...

Maybe one month ago the smaller one started hosting in a zoa colony out of nowhere. Then a couple weeks ago, the bigger one took over and is hosting in the zoa colony, and the smaller one went back to sleeping in their old spot.

Today my ac went out and the tank got as high as 83 degrees. I put a clip on fan on the tank and got it back down to 80.

Could the heat be causing the aggression? Or anyone heard of a sex change happening 3.5 years later?

I put the smaller one in a breeder box in the same tank to give it a break for a bit. Any advice?
 
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Bamzam

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I definitely wanted to put the bigger one in the breeder box but he was harder to catch. The small one had all but given up from the bullying and was just hiding above the return nozzle. So I went to net him instead and he didn't even put up a fight. I dont have much room in this tiny tank, so not sure how long I can keep this box here before the corals below it get upset. But the way it was going, I wasn't sure if the big one was gonna kill him

20200801_003559.jpg
 
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Bamzam

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Actually I should add one more event. Beginning of May, I added a six line wrasse. That lasted about 3 weeks. Not sure who started the fighting, but the six line was beating up on both clowns and trying to kill them. Rehomed the six line at the end of May. Then by end of June is when one of the clowns started hosting in the zoas. Not sure if maybe the removal of the six line led to them drawing out new territories? But that was a couple months ago.
 
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Bamzam

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I let the small one out of the breeder box and the chasing started immediately. Not just defending the zoa colony, its chasing him everywhere and won't let up. Tank has been steady at 78 since last night, so not sure if its the temperature causing aggression.

Caught the big one and put him in a breeder box for now, but not sure what to do with them. Pic of the small one with fins all torn up

20200801_125420.jpg
 
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