Sick Dwarf Neon Gourami

Hello everyone I hope you can help me. Here is a short history of my tank. It is about 3 months old, have had two fatalities recently, fish were newly bought - died within 6 weeks of purchase, these fish never ate, never saw them - this fish though still eats and is generally active but is now slow, laying on the bottom of the tank, swimming/floating sideways and sometimes and grayish yellow colour. Photo attached (hopefully!) makes him look better than he actually is. Water parameters are ok, will check again; change water 3 weeks ago 50% - this is when he started to look unwell after the water change, have added Aquarium Antiseptic and Stress Zyme, there are 3 other Gouramis in the tank, a pleco and a couple of other community fish (not sure on type), 75 ltr tank and haven't recently added any new fish.

First,you need to read up on cycling a tank.
http/www.fishforums.net/index.php?showtopic=10099
This would explain your deaths in the beginning. You say your water is normal, what's that? Do you have exact readings? You have to have some ammonia/nitrite in there at this point in time,which is very bad for the fish.

You need to do your water changes more often. Like 25% every few days until your cycle is complete. Your gourami looks very poorly,he needs clean water

thanks for the reply I`ll check the levels now and replace 25% of the water will ammo block help?

Yes,that will help a lot. If you can get ahold of some starter bacteria you will be good to go. Maybe your lfs will hook you up with a cup or some filter media? Or you can get the "bacteria in a bottle". I know Cycle and Bio-Spira are both good

Good luck to ya!