Strange Behaviour

[Lenna]

I bought an orange female mollie just over a month ago. Now although she looks perfectly healthy (bright colour, fins aren't pinched, eating) she will start swaying, almost thrashing from side to side for a few seconds every now and then. Is this some sort of motor or nervous disease? Or is it a symptom of something else? Please help I've never seen this before.

PS All other fish in tank are fine
ammonia 0
nitrite 0
pH 7
so not water otherwise others would have symptoms too.

 

[staredecisis]

Your description is kind of vague for me to make any assessment. In my tank there is an abnormally heavy current in one spot occasionally, fish passing through seem to have a frightful spasm. But really it is just the water.

How do you mean she is swimming from side to side? Is she just swimming back and forth? Or is she turning onto her side, in the water? If you can describe this behavior a little more, maybe someone here might be able to make something of it for ya...

 

[Loopyness]

Maybe its crazy? Or just messing around? Maybe it could be the current, like staredecisis said, my clown loaches love playing infront of the filter, nutters

 

[Lenna]

No, it isn't the current although it looks like she's swimming into a big current she does it anywhere in the tank. She thrashes her head from side to side for a few seconds then stops. It looks pretty freaky, I'm just worried.