I have a 37g with 7 black neons and 9 neons. I had a quarter sized angelfish and a 4 inch bulldog pleco. Both of them died and got encased in some mucousy looking stuff. The stuff is also on some wood and plant decorations in the tank. It appeared shortly after i brought a new aquarium plant home from petsmart. I dont know what this creepy thing is but im not putting my hand in the water till i know what it is! please help!