
Am a newbie, both here & with opae ula (but not new to aquatic life or shrimp keeping).

I have two small tanks, each one is a gallon.
One is (almost) a complete crash and the other is stable.
Tank one:
The almost crashed tank is nearing it’s end because there are only two survivors left

Sand substrate
Crushed limestone/coral gravel in the back
Black lava rock
Plastic coral decor
Tiny algae mossball from mustafa
I read only a few starting comments, but no followup in detail, just hypothesis.
So is it a disease? A few had “algae” (yellowish fluff) growing on their swimmerets. For some, the “algae” would be on their swimmerets AND antennae too.. When they’d swim, it would be frantic upward vertical jerks and then they’d fall backwards and start all over again. By the time the algae became visible to my eye, they’d constantly be sitting on the sand, not even trying to swim, visible algae on their swimmerets, and would constantly be fanning themselves, almost as if they were suffocating.
Pictures are of the last one taken out (sorry for the quality) Any comments on cause, prevention, or anything at all would be appreciated.
Also, if the last two surviving opae don’t make it (one has some fluff on its swimmerets and the other is very still on the sand, so it looks grim
