died with a fat belly

[mohammadali]

hello all
i had 2 Blenny Lawnmowe one had a really big and fat belly i thought it has egg in it it was 2 days ago , i looked into tank today one of them is dead with jelly around it

all the other fish and urchin and corals doing well
nitrate 0
PH 8.2 - 8.3
nitrite 0
ammonia .25
salinity 1.026