Storage is a part of the Retain Aspect of the Murk Fysa.
This is a passive fysa. Users' threshold of being poisoned is heightened, and they can hold inordinate amounts of fysa in the body safely. All mucus membranes are stained iridescent black as a result.
Users can spend several days in the ocean before needing to take a break (though said break will need to be a few days to metabolize and break down the fysa unless they have Burnoff or Vent). They can eat most fysa contaminated foods without worry.