hi , we have just changed our tank from having chichlids ( which we never had no probs with) to guppys ,neons , mollies ,and others like that. we also had 2 fighters , since we have changed a few of the new fish have been dying about 30% , we wake up and there dead but the fighters died within a few hours i noticed their mouth going white and the skin looked like it was coming off and started moving down the fishes body whith mor skin flaking of then died this whole process only took a few hours from getting a whie mouth to all the skin flaking then dying it also happend to my orange fish aswell but none of the other dead ones looked like they had this , i would really appreciate any help