Species Groups

Learn about the following species groups (including their most common members, as well as purchasing, storage and cooking information), or select a specific species from the species list on the right.

More Species Groups 

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Albacore
Thunnus alalunga
 
Bigeye Tuna
Thunnus obesus
 
Bonito
Sarda australis (Australian Bonito)
Sarda orientalis (Oriental Bonito)
Cybiosarda elegans (Leaping Bonito)
 
Longtail Tuna
Thunnus tonggol
 
Southern Bluefin Tuna
Thunnus maccoyii
 
Yellowfin Tuna
Thunnus albacares
 

Tunas

These torpedo-shaped fish with deeply forked tail fins and smooth, almost scaleless, bodies are built for speed. Large schools of them traverse great distances during annual migrations and they can eat up to a quarter of their body weight daily to maintain the energy needed by their muscular, streamlined bodies. Their active muscles are well supplied with blood, giving their flesh a distinctive red colour, making them one of our most highly prized fish, popular even among those who generally prefer red meat.

Tuna is the general name for a number of species belonging to the Thunnini (tuna) and Sardini (bonito) sub-groups (or ‘tribes’) of the Scombridae (mackerels) family. Three of these have major commercial significance in Australia:

Yellowfin Tuna (Thunnus albacares) is named for its distinctive long yellow top and bottom fins. Found right around the Australian coast, it is our most common Tuna. It can vary greatly in size from 4 to 100kg (50-90cm) and prime specimens are air freighted to Japan where they fetch a high price.

Bigeye Tuna (Thunnus obesus) has an almost cylindrical body and bigger eyes than other family members. It has a dark metallic-blue back with whitish belly and yellow-tipped fins and paler flesh, more pink than deep red. Caught mainly off the south-eastern and south-western coasts, it prefers warmer water temperatures, so supply is lowest during winter. While we do see some of it domestically, it’s mostly exported to Japan, where it is the second most popular sashimi fish.

Southern Bluefin Tuna (Thunnus maccoyii) is Japan’s most popular sashimi fish and a single specimen can command tens of thousands of dollars at Tokyo’s Tsukiji fish market. It’s fished to a very strict quota system in order to ensure a sustainable supply and, needless to say, almost all of it is exported to Japan, with the remainder going primarily to restaurants in Sydney and Melbourne. Caught primarily in the Great Australian Bight and off Tasmania, it is also ranched in sea pens off Port Lincoln. Fish ‘ranching’ differs from fish farming in that juvenile fish are herded from the wild into pens where they’re raised until they reach a marketable size. Attempts to breed Southern Bluefin Tuna in captivity are very close to succeeding, which should bring more of this prized species to the Australian market. This Tuna has blue fins, as its name suggests, but also a bright yellow keel on either side of the tail base and a yellow bar on the tail fin.

Other members of the Tuna family found in Australian waters include:

Albacore (Thunnus alalunga) is known as ‘the chicken of the sea’ because its paler, medium-firm flesh turns white when cooked. It also dries out quickly if overcooked and is less expensive than its more popular cousins above.

Bonito (Sarda australis and Sarda orientalis) these sleek silver fish with distinctive black stripes are smaller than other Tunas, commonly 1 to 4kg, and so often sold whole. The soft, creamy pink flesh is high in oil and good smoked, baked or barbecued.

Northern Bluefin Tuna (Thunnus orientalis), also known as Pacific bluefin tuna, shouldn’t be confused with Thunnus thynnus, the Northern Bluefin Tuna of the Atlantic Ocean and Mediterranean.

Longtail Tuna (Thunnus tonggol) has a distinctive slender body and tail and is sometimes mistakenly called Northern Bluefin Tuna. It schools with other Tunas and is caught as bycatch off Australia’s north-eastern coast. Its soft, brownish flesh is mainly canned or smoked.

Buying
Tuna is usually sold as steaks, cutlets or sliced as sashimi. Look for pinkish red to burgundy flesh (colour varies with species and cut) that is firm, lustrous and moist without any dull brown markings or oozing water and with a pleasant fresh sea smell. Always buy sashimi-grade fish if it is to be served raw or rare (see ‘Sashimi’ below).

Storing
Wrap steaks and cutlets in plastic wrap or place in an airtight container and refrigerate for up to 3 days or freeze for up to 3 months below -18ºC. Sashimi-grade fish should be eaten within 24 hours of purchase or cooked (see ‘Sashimi’ below).

Cooking
Tuna lends itself to a wide variety of preparations: poaching, pan-frying, stir-frying, baking, braising, grilling, barbecuing, smoking, and pickling. The firm flesh holds together well in soups, curries and casseroles and can be cubed for kebabs. Like any fish it will quickly become dry if overcooked and its rich, meaty texture means it’s excellent served rare. Some people prefer to remove the dark bloodline before cooking Tuna, while others enjoy its stronger flavour; it is best removed if fish is to be served raw.

Serving
Sashimi-grade tuna is luscious served raw as crudo (thin slices fanned on a plate, drizzled with olive oil and lemon juice), ceviche (marinated in lime juice, chilli and onion, tossed with finely diced tomato, capsicum and coriander) and, of course, sashimi (with wasabi and soy sauce). It’s also great quickly seared on a hot BBQ and served like rare steak; bring it out of the fridge about 30 minutes before cooking and rest it for 5 minutes afterwards. When cooked all the way through, the flesh breaks into lovely large flakes, ideal for tossing through salads or pasta.

Sashimi
‘Sashimi-grade’ refers to very fresh seafood suitable for eating raw (or rare). This is achieved by catching and handling the fish in such a way as to maintain peak freshness and quality. Fish are line-caught, landed onto a mattress (to minimise bruising) and killed instantly by brain-spiking (ike jime). This prevents the fish from struggling and releasing stress hormones and helps keep the body temperature low.

The fish is then bled immediately, removing heat and waste products, and put into an ice slurry to drop the body temperature as close to 0ºC as possible. Ideally sashimi-grade fish should be purchased on the day of consumption; after more than 24 hours in a domestic fridge, while it will still be premium quality, it will no longer be at peak freshness and should be cooked rather than served raw.