Your readings need some attention....
First off, have you let your tank go through the complete
nitrogen cycle? Did you take readings through the cycle period and prior to adding fish? I found that this is the best way to truly be sure your tank has fully cycled. If the tank hasn't completely cycled this will be a problem...I see that you have zero ammonia, but show .25 nitrites...Nitrites are more toxic to fish than ammonia and though it is only at a .25 reading it is not good for the fish. It will harm their immune system and make them more succeptible to disease. It is important to get this number to zero as quickly as possible. Do this through water changes. I would change 20-25% and take readings the following day. Keep monitoring for about a week to make sure that the readings are stable and perform water changes as needed to get that number down to zero. Your optimum readings should be: pH: 6.8-7.0, Ammonia: 0, Nitrites: 0, Nitrates: <20.
Treat each bucket of water you add back to the tank if using a small bucket. If you aren't already doing so, you may want to add live plants to the landscape. They will help with chemical breakdown and also can help stabilize your pH.
As for the dwarf gouramis - always: Buy in pairs (one male, one female) or solo....Even in pairs some will fight. Provide high cover for them as they are top dwellers. Floating plants or plants that grow tall will work well. Place a couple at opposite ends of the tank so that if they do spat they will each have their own place to go for cover. I keep only one male Neon Blue Dwarf Gourami and he think's he's king....Chases the swordtails around the tank.
If they have scale and/or fin damage you will want to treat them....I have never had this problem before so I am unsure as to what to recommend. Check with your lfs and they should be able to recommend the proper medication. Be sure to follow the directions properly.
Good luck!