Do nothing. It will taper out on it's own. It's a bacteria that is ubiquitous in your pond or possibly even in the gut of your fish. The bacteria only causes a problem if your fish are stressed for some reason.

Do you know of any potential stressors in your pond? Rough handling during catch and release? Handling fish in very warm or under 50 degree water? Too many fish in the pond? Recent turnover reducing oxygen levels? Sudden temperature changes in the pond? Spawning? Predator stress? Disturbances in the water like rock throwing?

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.