Viral sleeping disease /Carp edema virus disease（CEVD）
Symptoms
It mainly occurs to nishiki koi, they lie at the bottom of the tank and look like sleeping.
They will swim if you touch or stimulate them, but soon to lie down again.
It is also accompanied by hollow eye or bleeding from skin,
and then soon become weak until death.
Cause
It is caused by a virus called Poxviridae.
Countermeasure
0.5% saltwater is effective.
