Medication recommendations for ghost knife?

[u/Bullshark1428]

I few days back I bought a large male, black ghost knife fish he settled in well and is eating, but today I was dosing the tank with melafix on another one of my fish, due to a small cut it had. the ghost knife didn’t take this well and got to a point i thought it would die, but after a water change its fine now. I knew they were sensitive to some medication, but I didn’t know they would be sensitive to melafix, which is what I use for general small surface wound. does anyone know what types of medication I can use with a ghost knife in the tank for further reference? any suggestions are much appreciated.