Clownfish, lighting, & fighting...

[Daz_1978]

Have you ever witnessed...

I've had a pair of Ocellaris Clownfish for quite a while. The boss was established long ago, considering one was way smaller when purchased. There's never been much aggression, other than the "I'm still the boss" pecking here and there.

Over the holiday, my wife wanted to take some pictures of the family in the pet room. She told me to turn the tank lights off so that the pictures weren't all blue. I just switched to manual mode and went all white light.

After a minute or two the clowns started squaring up head to head and went to war!!! They were tumbling all over the place. The submissive one was no longer submissive and the more aggressive one was overly aggressive. It was WW3 in the tank and I knew I'd be down to just one clown if that kept on. I was prepared to move one to another tank.
After the photo session, I switched the blues back on... and all was normal with the world. The clowns started acting as if nothing had happened.
I scoured the internet to see what could have possibly gone wrong, and finally found one really old video on YouTube that showed the guy's clownfish doing the same. Being cool together in one type of light and instantly fighting like crazy in the other type of light.

I can only assume that they are used to seeing each other with the blue tint... and thought there were imposters in the tank with a slightly different color when the blues were off, and attempted to kill the imposter.

Has anyone ever witnessed that before???

 

[ISpeakForTheSeas]

I've seen this pop up a few times in a few different lighting variations - the idea that they couldn't recognize/accept that the other fish is their accepted mate is one I hadn't had before for it though:

For anyone curious, clownfish determine social hierarchy/desirability in large part by coloration (I'd heard it said by breeders trying to cross clownfish morphs that "clowns are racist" and it turns out it's actually kind of true).

My guess (I don't know for sure if it's accurate, but it seems plausible to me) is that the change in lighting drastically alters how the male clown looks to the female - if it makes it look substantially less desirable, then the female may be trying to drive it off in hopes of finding a more attractive partner; if it makes it look substantially more desirable, it may be causing the female to try and assert dominance through aggression rather than coloration.

Fun fact for anyone interested here, the UV reflectance of clownfish is also related to intraspecific aggression and their social hierarchy.***

***Source:

Higher ultraviolet skin reflectance signals submissiveness in the anemonefish, Amphiprion akindynos

When signaling submission, it is important to wave the “white flag.” In the Barrier Reef anemonefish, ultraviolet color patterns serve to signal submissive

academic.oup.com

 

[DCR]

Not really the same situation as yours but I once had a couple of tangs in a FOWLR under VHO fluorescents that were very old and dim. When I finally replaced them, the tangs instantly became much more active and started flashing one another. Same color bulbs but it did become more white. I generally think the bright white lighting has some benefit to the fish that we overlook. I know that my fish look much better under 10-14K metal halide lighting.