You see it all the time on fishing trips: Someone catches a fish that might or might not be long enough to keep, and the angler flops it down on an ice chest for a quick measurement on the built-in ruler.

If the trout’s tail touches the 12-inch mark or the redfish just makes the 16-inch minimum, the fish is quickly thrown into the box.

But that might be a mistake that could result in a ticket and costly fine, according to the folks at Lafitte’s Griffin Fishing Charters (800-741-1340).

“The danger is that people will sit on (the ice chest) and bend it,” Griffin’s Capt. Colby Creppel said. “That can throw off the measurement.”

Using one of those stick-on tapes that often can be found on the gunnel or the back of the front deck is little better.

“I’ve seen those things stretch,” Creppel said. “And they stretch and shrink with the temperature.”

Sure, if the fish breaks the magic mark by half an inch, you’re probably good to go.

But when you’re flinging schoolies in the boat hand over fist, an eighth of an inch can be the difference between a legal fish and a ticket from your friendly wildlife enforcement agent.

So what’s the best solution?

Griffin Fishing Charters owner James Arcediano said you have to have a solid measuring board like a Golden Ruler is the only way to ensure your fish truly measure up.

“You need something to push its nose up against,” Arcediano said. “That’s what the game warden is going to do.”