Hi there, not sure if anyone knows what this is, have been trying to find info on the internet but so far nothing close.
Our tank is the first on the sump system and hasn't spread to the other tanks and has been shut off from the rest.
Killed off all the guppies and the long fin bristlenoses, plus snails seem to be dieing when on the bottom.
Feels like a sludgey texture, is black and within a couple of weeks covered the substrate.
Seem to have layer about an inch above, when you put your hand in it stirs it up, maybe like a gas sitting under the water.
Ammonia came back stress level, others on the same sump are all safe.
Added a whole heap of snails thinking they might eat whatever it is, but seem to hang above the line and other dead on the bottom.
here is a link to some photo's
http://i1294.photobucket.com/albums/b60 ... d5f19f.jpg
http://i1294.photobucket.com/albums/b60 ... 4f61f9.jpg
http://i1294.photobucket.com/albums/b60 ... aa96b0.jpg