" under normal conditions,*Saprolegnia*fungi are harmless inhabitants of freshwater aquariums that attack dead and decaying organic matter"
"*Common targets are uneaten*fish food
*and dead fish that have not been removed from the aquarium, as well as infertile fish eggs."
" With rare exceptions, these outbreaks are a sign of poor aquarium husbandry that could be prevented"
http://www.fishchannel.com/fish-health/disease-prevention/farewell-to-fungus.aspx
oh, thats weird, where have i heard all of that before.
if the fungus isnt on your fish while theyre alive im willing to bet the slime is because of decaying matter in your tank, and you have high ammonia.
or you know, you could consider the other random suggestions that were grasped out of thin air, from people who havent seen it before, and not check your water to help narrow down possibilities, and just go ahead and nuke everything and cause way more work for yourself.
the first logical thing to do, would be to remove the decorations and see if water changes clears it up, if youre not over feeding, which you never answered.