OK I have a 55 gallon which turns out to be only a 46 gallon in Canada. I had two golden gouramis, 1 3 spotted gourami. I gave away one golden gourami away due to them fighting all the time and shredding their fins. All are female except a male dwarf gourami. Of the two that I separated I gave the smallest one away and kept the bigger one. The 3 spotted gourami is now at the bottom of the tank and its spots are not there anymore, instead of black they are white and it has now black strips up and down the hole body. I still notice that it's fins and tail is injured so I put some Tea Tree oil in, which will help heal them.
I did just move the tank and everything to my new place, so maybe that is it. All levels are normal, there is no smell coming out of the water, it's crystal clear.