Sand Flounder

How to identify sand flounder

• A flatfish with both eyes on the right side of the head. That side faces up as it lies on the seabed.
• A diamond shape with rounded corners, not the oval of the other flounders.
• A greenish brown upper side that can change shade quickly to match the sand or mud.
• A plain white underside, not yellow.
• The front rays of the dorsal and pelvic fins are joined or only slightly split, where yellowbelly flounder have deeply split front rays.

Sand flounder are flat, right-eyed fish: both eyes sit on the right side of the head, and the fish lies on its left side on the seabed with the eyed side up. The body is a distinct diamond shape with rounded corners. The upper side is greenish brown and can change shade quickly to blend in with the sand or mud underneath, and the underside is white.

New Zealand has four common flounders, all called pātiki, plus soles, brill and turbot. Shape and the colour of the underside separate most of them. Sand flounder is the only diamond-shaped one. Yellowbelly, greenback and black flounder are oval, and of those, only yellowbelly has a yellow underside. Another check is the front of the dorsal and pelvic fins: the first few rays are joined or only slightly split on a sand flounder, but deeply split on a yellowbelly.

Like all flatfish, a sand flounder starts life as a normal, upright swimming larva with an eye on each side of its head. As it grows, the left eye moves over the top of the head to the right side, and the young fish settles on the bottom.

Where it lives in New Zealand

Sand flounder live throughout New Zealand's coastal waters, in harbours, estuaries, bays and on open sandy coast. They are most common in shallow water, usually less than 50 m deep, but adults are found down to about 100 m, especially on soft seabeds. As the name suggests, they prefer sandier ground than yellowbelly flounder, which favour shallow mud. Both species also turn up on surf beaches. The main fishing grounds are the Hauraki Gulf, Tasman and Golden Bays, Hawke Bay, the Canterbury Bight and Te Waewae Bay.

Young flounder are carried by currents and tides into estuaries, harbours and inlets, and stay in the shallow, sheltered parts on mud and sand flats for up to two years. They then move into deeper water, including the deeper parts of harbours and the open coast. Adults spawn offshore in late winter and spring, and come back into the harbours over summer to feed.

Sand flounder ambush their food. They bury themselves just under the surface of the sand or mud, wait for prey to come past, then gulp it, often taking in a little sand, mud and weed at the same time. They eat crabs, shellfish, brittle stars, polychaete worms and anemones.

Sand flounder in enclosed waters tend to stay put. Fish tagged in Tasman Bay or the Hauraki Gulf have never been recaptured far from where they were released, though fish off the east and south coasts of the South Island can move long distances.

How to catch it

Netting: most recreational flounder are taken with set nets or drag nets in harbours, estuaries and coastal lakes. In the 2022–23 national survey, nets accounted for more than two-thirds of all flatfish kept, and more than 8 in 10 were taken from the shore rather than a boat. Set nets go across sandy and muddy flats where flounder move in to feed on the rising tide. Drag nets are pulled through shallow water by hand. Netting is tightly controlled. The rules cover how long a net can be, how far apart nets must be, how they are marked and how many you can have, and set nets are banned outright in marine reserves and in large areas set aside to protect Hector's and Māui dolphins. Some harbours have their own bans or seasons. Check the rules for your area before you set or drag a net.

Spearing (floundering): walking the flats at night with a torch and a hand spear, looking for the outline of a flounder buried in the sand, is a classic New Zealand way to catch them. Go on a calm, clear night around low tide, when the water is shallow and still. Spearing accounted for about a third of the recreational catch in the first national survey. The usual size and daily limits apply to speared fish, and you can't be in possession of undersized fish even if they are dead, so carry a measure and only spear fish you are sure are big enough.

Rod and line: a few flounder are caught on a line, usually by accident while fishing for something else on sand. To target them, fish small pieces of bait such as pipi, tuatua or squid on small hooks, or small soft baits on light jig heads, on a light running sinker rig cast onto sand. Flounder have small mouths, so keep hooks and baits small. See the bait guide for more.

Eating

Sand flounder has delicate, mild white flesh with a fine texture. Keep it simple so the flavour comes through: pan-fried in butter, grilled, baked or steamed. Flounder are thin, so they cook very quickly.

Many cooks leave flounder whole on the bone, gutted and with the head on or off, and cook them in a hot pan or under the grill. If you'd rather have boneless fish, a flounder gives four thin fillets instead of two, two from each side of the backbone, and a very flexible knife makes it easier. See how to fillet a flounder. Like any fish, flounder eat best when killed quickly and chilled straight away, so get them into an ice slurry as soon as you can (see how to bleed and ice your catch).

Recipes

• Whole crumbed flounder with lemon and Pernod butter (Allyson Gofton)
• Spiced flounder with barley salad and pickled onion (Seafood New Zealand)
• Fabulous fancy flounder (RNZ)

Good to know

Sand flounder are found only in New Zealand. Flatfish entered the Quota Management System in the 1986–87 fishing year as a single group (FLA) of eight species: sand, yellowbelly, black and greenback flounder, New Zealand sole, lemon sole, brill and turbot. Since September 2021, commercial fishers have had to report each species separately, which is slowly giving a clearer picture of each one. Commercial flatfish landings fell to 957 tonnes in 2023–24, the lowest since 1936–37.

There is no single stock assessment for sand flounder. Fisheries New Zealand monitors it by area using catch rates. In Hawke Bay (2025), sand flounder were about as likely as not to be at or above the target level and unlikely to be below the soft limit, after catch rates rose back to the target. Assessments for Tasman and Golden Bays (about as likely as not at or above target) and the east and south coasts of the South Island (very likely at or above target) date from 2020 and are now considered out of date.

Recreational fishers kept an estimated 41,627 flatfish, about 9.7 tonnes, in the year to September 2023. The national survey doesn't split flatfish by species, and flounder make up most of the catch. That figure is well down on the 95,859 estimated for 2017–18 and 143,619 for 2011–12. The average fish kept weighed only about 230 g. Three was the most common number kept on a trip.

Sand flounder grow fast and die young. Most live only 3–4 years, very few reach 5–6, and many spawn only once. Males mature at about 12 cm and females at 18–22 cm, depending on the area. They grow bigger in the south: up to about 30 cm in the North Island and 40 cm in the South Island, and females grow larger than males. To make up for the short life, a female can release from 200,000 to over a million eggs. Numbers swing a lot from year to year because the survival of young fish in the estuaries varies so much.

Using the Fisheries New Zealand length-to-weight formula for sand flounder, a 30 cm fish weighs about 330 g, a 35 cm fish about 490 g and a 40 cm fish about 700 g.

NIWA lists poor water quality, sediment, invasive species such as the Asian paddle crab, and fishing pressure as the main threats to pātiki. Its advice to fishers is simple: put the little ones back so they get a chance to breed.

Questions

What are the rules for flounder netting?

Set nets and drag nets have their own rules on net length, spacing, marking and how many you can use, on top of the size and daily limits for flounder. Set nets are banned in marine reserves, in dolphin protection areas and in some harbours, and some places only allow them at certain times of year. The rules differ by area, so check the table on this page and the rules checker before you set or drag a net.

What is the size limit for flounder?

Sand flounder have a lower minimum size than the other flatfish, and flounder count towards your combined daily finfish limit. The limits are set by MPI for each fishing area, so check the table above, which shows the current limits for every area and when we last checked them. Measure from the tip of the nose to the middle of the tail.

How do you tell the difference between sand flounder and yellowbelly flounder?

Turn the fish over. Sand flounder have a white underside and a diamond-shaped body. Yellowbelly flounder have a yellow underside and a more oval body. The front rays of the dorsal and pelvic fins are also deeply split on a yellowbelly, but joined or only slightly split on a sand flounder.

Is flounder good eating?

Yes. Sand flounder has delicate, mild white flesh with a fine texture. Cook it whole on the bone or as thin fillets, pan-fried in butter, grilled, baked or steamed. Flounder are thin, so they cook in minutes.

What is the Māori name for flounder?

Pātiki is the general te reo Māori name for flounder, and Te Aka Māori Dictionary gives it for sand flounder in particular. Other flounders have their own names too, such as pātiki-tōtara for yellowbelly flounder and pātiki-mohoao for black flounder.

When is the best time to catch flounder?

Summer. Adult flounder spawn offshore in late winter and spring, then come back into harbours and estuaries over summer to feed. For spearing, calm, clear nights around low tide give the best visibility in the shallows.