Dieing Fish Plz Help!

[GreatGenes]

okay so i have had a 90 gal tank up and running for about 6 months now and fish keep dying on me..some fish seem to have had fin issues where the fin had a white mark and looked kinda stiff other fish have died from unknown causes..and atm i have a blue groumai that looks real awful..his head has gone discoloured overnight..lastnight he seemed perfect. this seems to be the case alot at night they look great! and then the next day there belly up its a community tank that consistes of guppies balloon mollys some neon tetras and a couple other things..my water quality is good i have been testing. the ph, temp, ammonia is all good. ill include a pic of my groumai since hes still alive and maybe i can still help him.

 

[fluttermoth]

What are the actual numbers from your water tests?

Have you done any water changes recently? Cleaned out the filter? Do you always use a dechlorinator? I'm afraid I doubt if we can save your gourami; he doesn't look good, but we might be able to stop you loosing any more fish in the future.

As a first aid measure do a few large (50 or 60%at least) water changes (warm, dechlorinted water, of course!) over the next couple of days and see if that helps; fish are remarkably resiliant, so you never know; he may pull through

 

[micko]

+1.

Large water changes for definite.