it useally means its getting anoyed / excited or ready to attack something , this can be seen in all channa , but is best noticed on any red eyed fish esp marulia , on marulia it sends chills down your spine when you 1st see it . like someone has just turned the lights on in there eyes lol
Hi,yes it all depends on what kind of mood they are in,some fishes change colores,others shake or float to the surface ,swim in a stange way,its all there.