Classification of fish
There are many types of fish and when you only see fillets for sale, it is often hard to imagine what the fish looked like in its natural state. Generally speaking, fish are categorised as white or oily and then as flat or round. Fish are then described in terms of the texture.
Flat fish such as sole or flounder have a delicate flaky flesh which cooks in only a few minutes and they are often cooked whole and eaten off the bone at the table.
Snapper and tarakihi are both round fish and considered of medium texture as they flake into thick flakes and hold their shape during cooking. Salmon and monkfish are round fish that do not flake as easily and retain their shape while cooking.
Fish can be divided into groups - white fish and oily fish. White fish can be flat or round. Oily fish are round.
White flat fish: sole, flounder, brill
White round fish: snapper, ling, john dory, cod
Oily round fish: salmon, tuna, trout, mackerel
To scale and gut fish
To scale a fish, with the back of a knife scrap along the fish - tail to head. The scales will fly off so you need to wash you and the fish off in water.
To gut a fish, make an incision along the soft stomach skin, below the head. Pull out the innards.Wash the fish in cold water.
To remove the fins from a fish, cut the skin around them, grip and yank sharply towards the head to remove.
Filleting of round fish (such as snapper, tarakihi or gurnard)
I am by no means an expert at filleting and admire the skill of professional filleters who seem to deal to the fish at lightning speed. I am always impressed by the number of times the filleters sharpen their knives; etched in their sharpening stone is a genuine groove - proof of sharpening activity.
If you are buying fish it helps to have it gutted and scaled at time of purchase. To get rid of any stray scales, when you get home, you can rinse off the fish or fillets in cold water, pat them dry with a paper towel and cover and refrigerate.
Step-by-step instructions for filleting
Step 1: Cut off the head behind the gills. If you don't mind being stared at you can leave the head on if you wish to.
Step 2: Make an incision along the back bone from the head to the tail.
Step 3:
Working with short strokes and keeping the knife as flat as possible, gradually fillet across the bone to free the fillet, peeling back the fillet as you go.
Step 4:
As you work across the fish, you will come to the stomach area and this needs to be cut off and discarded.
Step 5: Turn the fish and do the other side.
Step 6: To remove the pin bones, run your fingers across the fillet, you will feel the bones that remain.
Step 7:
It is common for a small thin triangle to be cut out of the fillet to remove the pin bones. This is why whole fish appear to have a bigger and smaller side.
Step 8:
To remove the skin, hold the tail end and run your knife between the skin and the flesh in a gentle sawing motion towards the head, holding the skin firmly.