Process fresh salmon into Sushi / Sashimi salmon? I am a Sushi and Sashimi lover, especially salmon flesh. I recently bought some fresh salmon from Taobao. It's not frozen and has been kept around 4°C for 24h (during delivery). The product page said it's suitable for eating directly. After eating a few slices I noticed something different from what I eat at a restaurant. I see some white fluidy solid in my sauce plate, which is possibly fat. I washed the flesh and applied juice from squeezed lemon to it before eating. I'd never met this phenomenon before.


What's that white fluid in fresh salmon flesh? (No quality issues)
Is it fat? It does not dissolve in water or sauce.
How is this fresh salmon different from that in a restaurant?
How should I process the salmon so that it gets consistent with the one in a restaurant? Or simplifying this question, how can I get rid of the "fat" (since there's no other issue)?




Edit: I can now confirm it's fat. It's exactly the white layer between red layers(fresh flesh). How do I stop it from "washing off"?
Sushi fishes are usually flash frozen for a few days before being used for safety (to kill off bugs)
It might change the texture of the fish as it is unfrozen; the better the restaurant the better the fish will be unfrozen.

http://www.pbs.org/food/fresh-tastes/myth-sushi-grade/


  For fish that contain parasites, the FDA provides guidance under their
  Parasite Destruction Guarantee. This states in part that fish intended
  to be consumed raw must be “frozen and stored at a temperature of
  -20°C (-4°F) or below for a minimum of 168 hours (7 days)”.


As for the fluid, I don't know, maybe fat or just water with dissolve fish protein (the thing that turns white when you cook salmon).