Before any of this can be considered, though, we need to understand what it is we are actually looking for in regards to quality. Here are some things to look for when buying fish.

This is something you can check visually by looking at the scale coverage across the fish. The mucus basically provides protection to the fish in the open ocean by trapping pathogens that would cause disease.

Antibodies and enzymes in the mucus actively attack those pathogens to protect the fish. When an old mucus layer containing the pathogens is shed, it is replaced by new mucus and the pathogens are lost. Any visual damage or imperfections on a fish can suggest poor handling, prolonged direct ice contact or variable temperature control.

A fish's eyes should look bulbous, be risen slightly from the head and look moist, bright and clear. There are, however, times when a fish that looks spectacular in every other way can have cloudy, slightly foggy eyes. This is mainly due to the fish being chilled too quickly post-harvest.

Note: If you see a fish at the market with eyes that protrude considerably from the head, rest assured there is nothing wrong with it. This is an example of barotrauma, where a deep-sea fish has been caught at great depths and the large change in pressure caused by it being brought to the surface causes the eyes (and often also the stomach) to become more visually prominent than other species.

As not every supplier or seller will allow you to handle the fish they are displaying, it is best to revert to your nose. Even the fish I dry-age for upwards of 20 days carry little to no aroma. The only smells a fish should have are a light ocean water smell sometimes comparable to mineral-driven aromas, such as cucumber or parsley stems. If a fish smells "fishy", with an odour comparable to that of ammonia or oxidised blood, then it is best to avoid it. Unfortunately, no matter how much culinary genius you may possess, there is very little that can be done to rectify a fishy fish.

Fish force water through their gills, where it flows past lots of tiny blood vessels. Oxygen penetrates through the walls of those vessels into the blood, and, in turn, carbon dioxide is released. The redder the gills, the fresher the fish. Where slime and mucus are desirable on the outside of a fish, the gills should be slightly drier and clean of any debris.

If you see them it means the fish has been thawed and refrozen, which affects quality. Overall, in terms of flavour and texture, fresh farm-raised fish is often preferable if a wild-caught product is unavailable and frozen is the only option. But if you decide to go with frozen fish, just know that some fish types do better in the freezer than others - lean white varieties, such as snapper and cod, tend to become dry when frozen, but the fattier types, such as tuna and Spanish mackerel, should be fine even when frozen.

This is an edited extract from The Whole Fish Cookbook by Josh Niland, published by Hardie Grant Books, $55. Photographer: Rob Palmer 2019.

The richness of Australia's favourite nut, the macadamia, and the acidity and floral aroma of lemon yoghurt compliment this beautiful underused species of fish. Tommy ruff (or Australian herring) has a very clean, briny flavour and is full of good oils. It is a perfect fish for the grill. If you can't find tommy ruff, use mackerel, kingfish or sardines.

INGREDIENTS

4 small broccolini stems

2 tbsp extra-virgin olive oil

sea salt flakes

4 butterflied tommy ruff (herring)

lemon juice, to taste

Lemon yoghurt

1 lemon, preferably meyer

250g natural yoghurt, plus extra if necessary

sea salt flakes

Macadamia tahini

250g macadamia nuts

METHOD

1. Prepare a small charcoal grill, gas barbecue or chargrill pan for grilling the fish. (I suggest a small charcoal grill for best results.)

2. To make the lemon yoghurt, using a small knife, prick small holes over the lemon, then add to a saucepan and cover with cold water. Cover, bring to the boil and cook for 5 minutes. Drain the lemon and repeat this process two more times. This will result in the lemon being very soft and nearly all the bitterness of the pith will have been removed. Cut the lemon in half and remove the seeds, then blitz in a blender until very smooth. Transfer to a bowl, cover with baking paper to prevent a skin forming and chill.

3. Once the puree is completely chilled, mix with the yoghurt and a generous pinch of salt. If the flavour is still too strong, add a little more yoghurt. Set aside.

4. For the tahini, preheat the oven to 160C. Roast the macadamias on a baking tray for 15 minutes, or until a light tan colour. Tip the hot nuts into a Thermomix set to 70C and blend for 10 minutes until completely smooth and the consistency of peanut butter. Alternatively, blitz in a blender with a little warm water.

5. For the charcoal grill, make sure the grill is hot and the charcoal has cooked down to hot embers.

6. Brush the broccolini stems with a little olive oil and season with sea salt. Grill over a medium-high heat for 2 minutes, or until tender. Finely cut the stems into small discs while stopping short of the florets and set these aside in a warmed bowl.

7. Brush the herring skin with a little oil and salt, then grill, skin side down, on the grill racks over a very high heat for 2 minutes, being careful not to burn the skin. When the fish is 70 per cent cooked, remove from the rack and fold over so the fillets are sandwiched together.

8. To serve, place a spoonful of the tahini in the centre of a plate and spoon a small spoonful of the lemon yoghurt inside. Brush the broccolini with a little more oil and season with lemon juice. Place a pile of the cut stems and small florets on top of the sauces, then add the herring alongside.

Serves 4

The public school I attended in East Maitland had a memorable sausage roll, with just the right amount of seasoning, fat and crispness from the pastry. I wanted to try to replicate it by producing this version with fish. In the restaurant we serve this with a tomato sauce made from native bush tomato, but it's delicious with anything.

INGREDIENTS

4 square sheets puff pastry

plain flour, for dusting

Filling

375g ocean trout or sea trout belly

75g fresh scallop meat

500g white fish, such as bream, flathead or whiting

1 onion, grated on a box grater

1 tbsp salt

1 3/4 tsp ground white pepper

1 3/4 tsp ground fennel seeds

freshly grated nutmeg, to taste

15g chopped flat-leaf parsley

Egg wash

2 whole eggs

1 egg yolk

1 tbsp white sesame seeds

sea salt flakes

METHOD

1. Before starting, chill all the parts of a food processor capable of blending fish to a puree. Have a bowl of ice ready. Once the food processor is chilled, blend the trout, scallop meat and white fish separately into smooth pastes. Combine the fish purees together and season with all the remaining ingredients. Keep this fish puree chilled over the bowl of ice.

2. Mix all the egg wash ingredients together in a bowl. Arrange the puff pastry sheets on a lightly floured work surface and arrange large spoonfuls of the fish mix on the pastry in the shape of a log. Using egg wash, brush the surrounding pastry liberally, then roll into the shape of a sausage roll. Either fold up the ends of the pastry to seal or cut to expose the ends. Brush the sausage roll with egg wash and chill for 30 minutes until set.

3. Meanwhile, preheat the oven to 200C. Brush the sausage roll with more egg wash, then season with sea salt and bake for 15 minutes, or until the pastry is golden and the filling, when checked with a skewer, is hot to the touch. Serve with a generous spoonful of tomato sauce.

Makes 8

A fish burger that looks and tastes like a beef burger. The first time we cooked and ate this, I couldn't believe what I was eating. I would happily choose this over a typical burger any day of the week.

INGREDIENTS

4 slices cheddar cheese

4 white burger buns, halved

60ml barbecue sauce

12 discs of Lacto-fermented cucumbers (see recipe)

4 slices bacon, fried until crisp (optional)

4 trimmed iceberg lettuce leaves

sea salt flakes

Patties

40g ghee

200g French shallots, finely diced

100g yellowfin tuna trimmings

1 tbsp salt

200g yellowfin tuna loin

200g yellowfin tuna red muscle

1 tsp ground black pepper

1/2 tsp ground fennel seeds

50g diced Murray cod, cobia or hake fat

2 tbsp extra-virgin olive oil

Salt & vinegar onion rings

2 tbsp castor sugar

500ml malt vinegar

80g salt

4 onions, sliced into 1cm-thick slices, tiny centre rings removed

2 litres cottonseed or sunflower oil, for deep-frying

50g rice flour

1/2 quantity Fish and chips batter (see recipe below)

METHOD

1. For the patties, heat the ghee in a saucepan over a low heat, add the shallots, cover with a lid and leave to sweat for 10 minutes without colouring. Blend the tuna trimmings with the salt in a food processor to form a pink paste.

2. Coarsely chop the tuna loin into a mix that resembles beef mince. Do the same to the red muscle, then stir this into the paste with the tuna loin. Add the pepper and fennel, then the diced Murray cod fat. Chill for at least 30 minutes. For the charcoal grill, make sure the grill is hot and the charcoal has cooked down to hot embers.

3. Shape the tuna mix into four patties, weighing 120g each, pressing them down lightly so the thickness doesn't exceed 2cm. Brush with the oil and leave at room temperature before grilling.

4. Grill the patties on the grill rack for 4 minutes until well caramelised on both sides. With a minute remaining on the second side, place the cheese slices on top and gently melt, then remove and leave to rest.

5. For the onion rings, bring the sugar, vinegar and salt to the boil in a pan. Separate the onion into individual rings, then cook a handful of onion rings in the pickle liquid for 1-2 minutes until just softened. Remove with a slotted spoon and repeat until they are all cooked.

6. Heat the oil for deep-frying in a large, heavy-based saucepan until it reaches a temperature of 180C on a cooking thermometer. Dust the onion rings lightly in flour and coat in the batter. Drop each ring into the oil slowly and fry until light golden brown. Drain on paper towel and season with salt.

7. Lightly toast the burger buns over the grill. To assemble, put a spoonful of the barbecue sauce in the centre of a base, add a patty, followed by pickles, bacon, if using, lettuce, a little more sauce and the top of the bun. Press down and serve with the onion rings.

Serves 4

INGREDIENTS

90g fine salt

3 litres water

1 tbsp toasted fennel seeds

2 tbsp whole black peppercorns

2 garlic cloves, crushed

1 kg small pickling cucumbers

METHOD

1. For the fermented cucumbers, combine the salt, water, fennel seeds, peppercorns and garlic in a very clean large bowl with a pouring lip and stir until the salt is completely dissolved.

2. Wash the cucumbers thoroughly to remove any debris, then place them inside a large sterilised mason (kilner) jar. Pour the brine over the cucumbers and place a small square of baking paper on top to keep the contents submerged. Seal and leave to ferment in a cool place for at least 4-5 weeks before consuming. Once opened, store in the refrigerator.

INGREDIENTS

215g self-raising flour

400g rice flour, plus extra for dusting

2 tsp baking powder

2 tbsp honey

345ml vodka (37 per cent proof)

550ml beer

METHOD

1. For the batter, whisk the flours and baking powder together in a large bowl.

2. Mix the honey and vodka together well, then pour into the flour mix. Add the beer and whisk together. Chill until needed.