My homemade cough syrup cures cancer, neurological disease, athlete's foot, heart failure and Covid. If you believe that, you can buy a 'cure all'. There is no such thing, and nothing that even comes close. Melafix smells very nice so it's close to cough syrup, so they'll sell you that. It's for you to feel you've done something, not for your fish.
There are remedy sellers lined up to liberate you from the burden of your money, but.
Predatory fish in tanks tend to have short lives, because every store bought feeder is a booby trap. Eventually, one goes off and everything dies. They are expendable, mistreated and usually diseased. I see a lot of columnaris/flavibacter in feeder tanks, as well as the incurable, untreatable, survives even bleach fish tb.
When my curiosity about a weird fish, like my old pike gouramis sucks me into keeping predators, feeders have always been the real killers. I simply will not keep fish predators again because of them. You can't breed food fast enough without huge tanks, and if you buy, you buy deadly diseases.