One interesting sight on the Mt. Vernon Trail in Arlington, Virginia last week was where a branch of the trail went under a roadway beside a tributary of the Potomac River.  There were a couple of young guys with fishing poles doing the fishing thing.  That’s always rather nice to see in an urban area.  What they were fishing for turned out to be feral koi that could be seen finning around in the murky shallows.   Some of these giant goldfish were more than a foot long in all their orange, black and white glory.  Happily the guys were doing catch-and-release on the koi.