Yeah I was thinking about doing the Melafix thing to treat it, but I was wondering if anyone knew how this happens in the 1st place. Its not Fin Rot or Fungus, and it doesnt look like a bite... It looks like someone took a razorblade and made a 1/4" long slit down the middle.
It seems like one of them has already started healing on its own so I guess its not water conditions... I drain and refill my sump (20 gals) every week... and Im adding the same additives everytime (DIY African Cichlid mix)