Why is this damselfish biting this octopus?

Is this Dascyllus trimaculatus feeding on this Octopus cyanea, or defending its eggs, or just bullying it, or what? All suggestions welcome!

(from Richelieu Rock, Thailand)

Damsel fish normally defend a patch of algae that they feed on. The octopus is probably righth on top of it.

Cool footage Nick!

I know the male Damsel fish down here will harass and even nip at divers when you get in

their turf while they are guarding a clutch of eggs on their manicured lawn.

Cheers,

Jim.

Really interesting video Nick. Never seen that before with Damsels except for the related Anemone/Clown Fish species, which will defend their patch against all comers, me included. They seem to be more persistant when they have eggs or tiny young so I assume this damsel was doing the same.

Thanks for the replies. Aggressive defence is what I suspected. At the time of shooting, years ago, I thought that the fish was feeding on the octopus. These Dascyllus trimaculatus are probably the most aggressive fish, for their size, in the Andaman Sea. More so than any of the clownfish. I'm really glad they're not titan triggerfish sized!