JFE is an antibiotic--I never recommend using antibiotics on fish that are not sick. Unnecessary use of antibiotics only provides bacteria with an opportunity to develop a resistance to the medication, leading to super strains of bacteria. This medication will do nothing but weaken your fish and kill all of the beneficial bacteria in your tank, so you have to cycle it all over again. It's a bad idea.
Keep in mind that common bacteria like columnaris are present right now in almost everyone's aquariums, even the most healthy ones. A healthy fish in optimal conditions will not get sick even when they are exposed to the bacteria because their immune systems are strong enough to fight it off. Getting a weak dose of antibiotic and killing off your beneficial bacteria may put enough stress on them to cause them to become ill.
In my opinion, if you are worried about your fish, simply increase your water changes and thoroughly vacuum your gravel. Give your fish everything they need to strengthen their own immune systems.