Real clowns are nothing like nemo, they are territorial and will pick and bully things in their turf that they dont like, esp if its something you just added, and esp esp so during their spawning cycles (if yours is paired) they are super aggressive
It's the larger one of the two so the female but watching more closely she is not biting she is rubbing . Mabey she thinks it's am anemone? I have two flower pots a blue and a green she is rubbing on the green one
Yeah, clownfish are very territorial and should be kept either in a pair or by them selves but if you have a big enough tank they would get alpine fine with there tank mates. But for now you should just move the goni on the other side of the tank where the clownfish do not go to.
My tank is a 75 I'm 105 over all . My clowns don't bother or get bothered by the other 12 fish in my system. I moved the goni and she followed it . I chased her off of it she stayed away for a few seconds and went right back.