twitching perula's

[nanotwelve]

Any idea why my clown's twitch sometimes. For no apparent reason one or both of my false percula's will begin to twitch as if they were getting some kind of electric shock. I thought maybe it was some kind of mating thing because they swim around each other when this is going on, and then sometimes when in different parts of the tank.
I was reading about pods the other day and read that when the pods are in their larval stage they can be on the fish and cause the fish to twitch. This only happens occasionaly but I thought I should put it out there. :thinking:

 

[devilboy]

this is the clowns way of setting a dominace between to the 2. once they establish the dominant of the 2, that one will grow quite larger then the other one. the larger one turning female while the smaller one will be the male