Clowns having seizures

[class clown]

I've had a pair of healthy false percs for almost a year now (my very first fish). They are doing well but every now and then they have these weird seizures where they'll be swimming normally then suddenly stall, start shaking somewhat violently in the same place for a second or two, then keep swimming normally as if nothing happened. They'll both do it every few minutes for a day or two, then they won't do it again for weeks or months. Is this normal or is this a sign of stress? I've noticed this happened twice after a partial water change (15-20%). I have a 29 gal. Eclipse FOWLR, ph at 8.2, ammonia, nitrates and nitrites all at 0, salinity .023-.024

 

[diverva]

How are they doing the seizures. Mine usually do it in a T pattern. The reason why they are doing this is they are trying to establish which is going to be male and female.

 

[aileena]

It is strange isn't it??? I have the same problem with my 2 green Chromis. 29g with 20pds of LR. Recently I purchased a 9 watt UV Steralizer for my tank and started to feed garlic every other day. I added another Chromis 3 days ago and he hasnt shown any shaking signs yet. I really don't know what it is either, but I have the same problem. I cannot treat with any copper either since I have inverts!

 

[class clown]

I'm hoping it's something along the lines of what diverva said. One of the clowns (I think the small one) does the shaking while pointing straight up, so it could be a T pattern. The fact that they both do it together while all other fish and inverts seem unaffected makes it seem even more like some kind of "ritual". Maybe I'll have a little clown family swimming around soon?
BTW, diverva, how does your bicolor treat your percs? I have a bicolor too that sometimes bothers the percs and is always after my new royal gramma. Might have to get rid of him soon

 

[diverva]

My bi color doesn't pick on my percs. He is small though. Once the clowns finished trying to find out who was who the female started to get darker and bigger. Right now she is about the size of the bi color. She is pretty territorial and doesn't let anyone else around her. Her and the Bi color do try and pick on the red lip blenny though. They have a tough time catching it. I created a lot of hiding spots to help keep it protected.