Sudden Death

[Mikaila31]

I just had one of my sparkling gouramis die on me. I found him floating through the water this morning. He was alive and breathing, but wouldn't swim. I could find nothing wrong with him. I put him in a cup with a little water, so he was close to the surface and could breath. But 30min later he was dead.

All the other fish look like they are in great condition. The rainbows are displaying to each other. The 4 other sparkling gouramis in their are displaying to each other and clicking like they normally do. These fish spawned just a couple days ago and the fry are in a container floating in the tank doing well so far.....


I'm totally stumped

 

[WILDER]

How many gallons or litries is the tank.
How many fish and which type.
Water stats in ammonia, nitrite, nitrate, and ph.
How old was the fish.