It is not a double dose. A little in the food is not a full dose. Anyway, it sounds like the fish is very ill and won't eat anyway. Kanaplex is absorbed through the skin too. I would start out with that. I dont know if the wounds are healed either, the OP said they have gotten better, but I'm not sure what that means. Seachem states that Kanaplex does not affect an established biofilter.I would not start out with Kanaplex, and especially not a double dose of putting it in the water and in food. Sores and other open wounds can be easily treated with non-antibiotic medications. It sounds like the sores are largely healed on this fish. Otherwise, we have no solid indications of a bacterial infection, so dosing an antibiotic (especially a very powerful antibiotic like kanamycin) might be needlessly putting stress on your fish and your biofilter.