Like Goose said, I think the term "running" was always used with "schooling" fish on the move, normally baitfish or consumable bait-fish that normally "run" in schools for either migratory reasons or to spawn. For example; ...the Fall "run", the herring "run", fish on the move for one reason or another ......either that ....OR... A couple of red-neck fishermen were watching the "Boston Marathon" on T.V. ...a loooooooong time ago and while watching one said to the other...
"Hey Earl.....lookeee there...thems all look like a bunch of fishes runnin' on those there streets...."
..your best bet is to just be honest, whether your catching or not.........NO, they are not
running.
..back to the solitude of you, your son, and the fish.