While I would never go against the judgement of your local fishmonger, here are few tips to choose a fish in the supermarket, . It works in three sensory steps ; appearance, texture and smell.
First of all let’s check a whole/gutted fish.
Eyes : bright and bulging, a clear cornea and shining black pupil.
Gills : glossy, bright red or pink.
Skin : glossy, scales adhering tightly ; clear mucus if present.
Firm and elastic to touch (ask the sales assistant to do it for you. You will notice that the marks made by his/her finger on the skin are visible for a second or two if the fish is fresh).
Skin : glossy.
Flesh : Raw looking, transparent, no bruising or blood spotting.
Firm and elastic to the touch (ask the sales assistant to do it for you. You will notice that the finger marks left by his/her hands on the flesh will only last a second or two if the fish is fresh).
Inoffensive, slight sea smell.