I have 2 plecos, 17 inch and 14 inch, with an arowana, 2 oscars and a bala. The other night I left my smokes in the livingroom and when I turned on the light my plecos were swimming in a circle, like they were trying to catch the others tail. Is this a breeding thing?? They seem to only do it at night. They've been trashing the tank pretty good. Morning ritual is too fix the plants, and they say osacrs are bad with plants. Is there any way to tell the sex. They're big enough so identity should not be a problem. I should mention that the next morning there was a concave in the gravel where they hang out the most. What should I do? Babies won't live in that enviroment.