usually my 4 reds dont do fu** all except sit there in a row but the last 2 days they have acting weird.swimming one by one straight after one another into the filter outlet.then turning their back to it and pausing for a few secounds then breaking the water surface with thier tail fin. they have been doing it for hours today its the strangest thing to watch.i tried to video it but the tank has no lights so you cant see nothing