I've had my elongatus a for 2mo. now, he's creeping up on 5"- hardly the most active P I own. The 11" Caribe and the 9" Nett. are way more active - non stop w/ lights on. When the Nett was small he was very unactive as well. I think size and age of the P have more to do with it than species, tanksize, lighting, or decor. Perhaps this why their are so many EX Piranha owners and the full grown ones are so damn pricey. PPl just don't want to see 75 gal of driftwood and rocks for perhaps a few years.
