New Zealand flounder
| New Zealand sand flounder | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Pleuronectiformes |
| Family: | Pleuronectidae |
| Genus: | Rhombosolea |
| Species: | R. plebeia |
| Binomial name | |
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Rhombosolea plebeia (J. Richardson, 1843) |
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The New Zealand sand flounder, Rhombosolea plebeia, is a righteye flounder of the genus Rhombosolea, found around New Zealand in shallow waters down to depths of 100 m.
New Zealand dab, pātiki, diamond, tinplate, square flounder.
Like other flatfish, the larval sand flounder begins its life with an eye on each side of its head and a round body shape, swimming upright through the midwater. As it grows out of this larval stage entering the juvenile stage one eye moves to the right side leaving the other blind and it takes on a flat diamond shape swimming flat/parallel to the ground. On the right side, the fish is a greenish brown dark colour or grey with faint mottling and on the left side (the side it lies on without eyes) it is white. The average length of an adult sand flounder is 25–35 cm with the maximum being 45 cm. In the day time, they lie on the seabed camouflaged almost perfectly in sand or mud; they have special pigment cells on their skin that can change colour to match their background, their protruding blue-green eyes being their only giveaway. They swim in a flowing style with an undulating movement of the side fins and when threatened by predators their tail is used for propulsion. Technically the adult swims on its side with the continuous dorsal fin fringing one edge of its diamond shaped body and its extended anal fin on the other. It has no swim bladder and only leaves the seabed for courtship and spawning activities.
Sand flounder are native to New Zealand so they are not found anywhere else in the world but they are found all over New Zealand.
New Zealand sand flounder is found in a majority of coastal waters around New Zealand. Its largest population is found at Tasman Bay and on the East Coast of the South Island. Around New Zealand they can be found in harbours, inlets, bays and open water.
They prefer coastal areas and are found in waters up to 50m deep but rarely deeper. They can be found in harbours, inlets, bays and open water. They are common on mudflats but seem to have no preference of bottom substrate as they are also found on sand, clay, pebbles and gravel bottoms. They also can be found in estuaries. When they are juveniles they are found in sheltered inshore areas such as estuaries, mudflats and sand flats where they will stay for around two years. They also prefer a temperate climate.
The geographic location of the New Zealand sand flounder determines its spawning period. In the north, it has a long spawning period from March to December. In the south, spawning largely occurs in the spring. A study in the Hauraki Gulf found sand flounder lay between 100,000 and 500,000 eggs when spawning. The variation in the number of eggs laid was attributed to the difference in size of the female laying the eggs.
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Wikipedia