Not sure if this is a disease. Just gonna give you a quick run down of what's happened and maybe someone can identify the problem.
Recently replaced the gravel in my 10 gallon with sand. Since then, here's what's happened:
1. Plants start to die off. Wasn't too worried; fish seemed fine, and I figured the plants might not like the change before I did it, anyway. I added the recommended amount of plant growth stimulator <--- (might be the problem if this is algae).
2. Translucent light brown membrane fuzz starts to grow on things. My Cory's algae wafers are covered in the stuff within hours of my having put them in the tank. The fish won't eat them once this happens. Same happens to any flake food that makes it to the bottom of the tank... covered with fast-growing muck.
3. Today, one of my Corys died. I'm guessing it happened within the last 12 hours because he was alive yesterday. The thing is, his body was covered with the same membranous stuff, and not a small amount of it, either.
Now, while I know decay happens differently underwater than it does above, none of this has happened before. Uneaten Algae wafers used to just break down into smaller pieces and eventually liquidize. I've had fish die before now and don't recall there being membranous fuzz all over them when I retrieved the bodies.
Is this just an aggressive algae? I do water changes weekly. Test strips tell me everything is in order, chemically. Afraid I might lose some more fish over this. BTW, tank population is 5 neons, 3 rasboras, and 2 corys. The tank had been fine for 6 months... then I added sand, and that brings us to today.