Introduction

New Zealand has a small fauna of native fresh-water fishes, consisting of about 34 species grouped in 8 families. The fauna includes none of the primary fresh-water fishes — groups which are restricted entirely to fresh-water; in fact, all the families are described as peripheral fresh-water fishes, characterised by the ease with which they tolerate brackish or fully marine waters. Increasing numbers of New Zealand fresh-water species are being found to have marine dwelling stages.

The fauna is a mixture of Indo-Pacific and southern temperature derivatives which have dispersed to New Zealand, probably from Australia (the southern forms) or South-east Asia via Australia (Indo-Pacific forms). The southern temperate forms are the most numerous. One family (Cheimarrichthyidae) is endemic to New Zealand and its affinities are uncertain. Fresh-water fishes have been able to reach New Zealand, in its isolation from other land masses, because of high tolerance of sea water, and it seems unnecessary to postulate land connections between New Zealand and other land areas to explain the presence of fresh-water fishes in New Zealand (see McDowall, 1964a).

Numerous attempts have been made to introduce fresh-water fishes to New Zealand; Thompson (1922) listed 30 species, mostly from the Northern Hemisphere. Many of these were Salmonidae, and of the 13 species which have succeeded in New Zealand, most are Salmonidae. As a result of these introductions, New Zealand has a famed brown and rainbow trout fishery; also a likely result of introducing these fishes is the almost certain extinction of Prototroctes oxyrhynchus. This species, once abundant, has not been recorded alive since 1923. Other species (e.g. Galaxias argenteus) also appear unable to compete successfully with trout and are rapidly becoming rarer. Such happenings sound a warning which should be heeded when the introduction of further predatory game fishes into New Zealand is considered.

The native fauna appears to be peculiarly restricted to smaller streams, although this may be only a reflection on the problems of collecting small fishes from large swift rivers. Most species page 90 are found in small gravelly streams or creeks, occurring beneath logs, overhanging banks or boulders. Even those species which are found in the larger rivers are sometimes more abundant in nearby tributary streams. An exception to this is Cheimarrichthys fosteri, which has adapted to the unstable environment of riffles in shingle rivers. Very few of the native fishes are commonly known, even to fishermen; some like the eels (f. Anguillidae), the whitebait (f. Galaxiidae) and smelts (f. Retropinnidae) are often seen and well known but others are secretive and dart for cover when disturbed. Further species are seldom seen because they are nocturnal hunters. The smelts and Galaxias attenuatus are the only truly shoaling species, and Prototroctes oxyrhynchus, the so-called ‘grayling’, is probably the only species to have had trout-like, ranging, pool dwelling habits.

The aim of this guide is to enable the reader to determine the families of the native and introduced fresh-water fishes. Two common estuarine families are also included. For the introduced and estuarine families, the species occurring in fresh-water are listed and brief notes appended. For identification below family level, the keys have been confined to the native fresh-water families. Having determined the family to which the native fishes belong, the reader is referred to secondary keys for each family which will usually enable identification to species level. In some cases present descriptions do not permit identification to species by means of a key; hence species groups are indicated in the keys. This problem is particularly severe in the f. Retropinnidae, in which distributional data have been heavily relied upon for specific identification. By necessity, some of the key characters are not easy to determine in specimens, and for this reason notes on distribution, habitat, life history and structure are given in brackets below the key characters for each species. Difficulties in the construction of keys also occur when juveniles are taken into account. Except in the case of Geotria australis, no allowance has been made for the separation of juveniles by means of the keys. Geotria australis has three distinct life-history stages in fresh-water, and notes have been included for the recognition of these stages. Sexual dimorphism occurs in all New Zealand Eleotridae, and it may therefore appear confusing that two fish with quite different colouration and rather different proportions key out to the same species (compare Figs. 11 and 12). Literature on New Zealand fresh-water fishes is listed in a recent bibliography (McDowall, 1964b).

Criteria used in Keys

Abdominal pelvic fins — pelvic fins inserted on abdomen, usually well behind pectoral fins.

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Adipose dorsal fin — a small fleshv fin without supporting rays, dorsally behind rayed dorsal fin.

Anadromous — species migrates upstream, usually from the sea or a lake.

Anal fin — fin mid-ventrally, behind vent.

Biserial teeth — teeth in two, usually parallel rows.

Canines — enlarged jaw teeth.

Catadromous — species migrates downstream usually into the sea or a lake.

Caudal fin — tail fin.

Caudal peduncle — posterior part of trunk between anal and caudal fins; length measured from base of last ray of anal fin to hypural crease; depth measured as least vertical dimension.

Colouration — refers to colouration of fresh specimens.

Compressed — laterally flattened.

Depressed — dorso-ventrally flattened.

Dorsal fin — median, unpaired fin on dorsum of trunk; one or more may occur.

Entopterygoidal teeth — present on paired bones forming roof of mouth behind vomer.

Flange of caudal peduncle — compressed, fleshy, dorsal and ventral expansions of the caudal peduncle.

Genital papilla — small protuberance behind vent, carrying the openings of the reproductive organs.

Gill rakers — bony filaments along the anterior edges of the gill arches.

Head length — distance from tip of snout to posterior margin of opercular membrane (H.L.).

Hypurals — the modified last few vertebrae which support the caudal rays.

Hypural crease — crease formed at the end of the caudal peduncle by bending the caudal fin to one side; the crease forms at the junction of the hypurals and the caudal fin rays.

Jugular pelvic fin — fin occurs anterior to pectoral fin base.

Keel — a semi-bony ridge along the mid-ventral abdomen in front of the vent.

Lacustrine — lake dwelling.

Maxilla — paired bone in upper jaw, behind and adjacent to premaxilla.

Median — in dorso-ventral midline.

Origin of fin — anterior point of attachment of fin to trunk.

Pre-maxilla — paired bone forming front of upper jaw: toothed.

Pyloric caeca — tubular sacs arising from posterior end of stomach.

Ray — soft, bony rod supporting fin; may be branched or simple, but always in adjacent pairs and segmented; such a fin is soft rayed.

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Relative positions of fins — refers to the relative positions of vertical lines through fin origins.

Snout profile — outline of head from tip of upper jaw to above eyes.

Spine — firm, bony rod supporting fins, unbranched, unpaired and unsegmented; such a fin is spinous.

Standard length — distance from tip of snout to hypural crease (S.L.).

Thoracic pelvic fin — fin positioned below pectoral fin bases.

Uniserial teeth — teeth in a single row.

Vomerine teeth — teeth on vomer, a bone situated medially in the front of the roof of the mouth behind the pre-maxillae.

Vent — posterior opening of the alimentary canal.

Vertebral count — number of vertebrae from head to caudal fin, not counting hypurals.

Annotations

Some of the criteria used in the keys are relative, e.g. jaw length, fin positions, and others are a little diffcult to use, e.g. entopterygoidal teeth, gill rakers, making the keys more difficult to follow. To minimise this, notes have been added below the key characters for each species. These notes include information which helps to confirm identifications, e.g. general shape and form, structural characteristics, colouration, distribution, habitat, marine phases, migratory habits and maximum size attained. While these do not produce absolute separation of species by themselves, when they are used in conjunction with the key characters, they should make identification more simple.

Key to Families

Introduced Families

F. Ameiuridae Ameiurus nebulosus — catfish (N.Z.) or brown bullhead (U.S.A.). Introduced from the Great Lakes region, U.S.A. Stoutly built, scaleless, with the first dorsal fin having a stout erectile spine anteriorly; 4 pairs of barbels occur around the mouth. Brown to olive green in colour, growing to about 40 cm. It is uncommon in New Zealand except in parts of the Waikato River system.

F. Cyprinidae. Tinca tinca — European tench. Stockily built with a pair of barbels at the corners of the mouth, small, deeply embedded scales and truncated caudal fin; olive-green in colour. It grows to about 75 cm., but is usually smaller; rare in New Zealand.

Carassius auratus — Prussian carp or goldfish.

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Carassius carassius — Crucian carp. Both species introduced from Europe or Asia. They are stout bodied with prominent scales and a long, high dorsal fin; olive to silvery-grey in colour, variants orange-red or pearly; known to grow to 75 cm., but usually to about 20 cm. Common in some localities.

F. Percidae. Perca fluviatilis — European perch. A deep bodied fish, well covered with moderately large scales; a distinct hump often occurs behind the head, carrying the large, flag-like dorsal fin which has sharp, rigid spines. Beautifully coloured; silvery green with a darker back and bright orange-red on the pelvic, anal and lower caudal fins. Grows to 25 cm., or more. It is successful in New Zealand in lagoons, coastal lakes and sluggish, weedy rivers.

F. Poecilidae. Gambusia affinis — mosquito fish. A small, live bearing species introduced from North America. It has a flattened head and upturned terminal mouth; the male has the anal fin modified to form an intromittent gonopodium. Silvery in colour. The male is smaller than the female, lengths 35 mm., and 60mm., respectively. Not widespread in New Zealand, but locally very abundant in northern areas.

The trouts, salmons and chars were introduced from North America and Europe with varying success. Salmo trutta and S. gairdneri are by far the most successful and widespread in New Zealand. They are large, rather slender, graceful fish with a good covering of small, firmly embedded scales. River dwelling fish are usually dark coloured with a variety of coloured spots on the dorso-lateral trunk; lake-dwelling and sea-run fish are usually silvery coloured with less prominent markings. In contrast with many native fishes, they inhabit open pools and tend to be more mid-water swimming fishes. They grow to a large size, up to 100 cm., but are usually smaller, commonly 30-75 cm.

Estuarine Families

F. Blenniidae. Tripterygion sp. — blennies or cockabullies. Small, stout, heavily scaled active fishes, bottom dwelling in tidal estuaries page 95 and rock pools, penetrating a short distance up lowland streams; mostly marine. Usually dark grey-brown in colour, they grow to about 100 mm., and occur throughout New Zealand.

F. Mugilidae. Aldrichetta forsteri — yellow eyed mullet. Erroneously called herring, it is a slender, fast swimming, shoaling species which moves into river estuaries with the rising tide and will move beyond estuarine waters into lowland rivers. Its scales are easily dislodged. It is bright silver in colour with a deep bluegreen back and a bright yellow eye; grows to about 45 cm., and is New Zealand-wide.

Mugil cephalus — grey mullet, in some localities known as fresh-water or jumping mullet. Similar to A. forsteri, but is more heavy bodied with a broader head and larger scales. The eye of M. cephalus is covered by a thick, fleshy, adipose eyelid which is divided into two halves by a vertical slit. M. cephalus may penetrate many miles up rivers and may be seen jumping from the water as it moves. It grows to about 70 cm., and is mostly a northern species in New Zealand.

Key to Indigenous Species

F. Geotridae — lamprey.

Partially fresh-water dwelling and semi-parasitic. There is one species in New Zealand; genus Geotria.  G. australis Gray.

(Three life-history stages:—

Form slender, trunk rounded with swollen branchial region, a hood surrounding a small oral sucker, no obvious eyes, one continuous fin-fold; grey-brown in colour; muddy backwaters and pools; 85 mm. Ammocoete — larva.

Form slender, slightly compressed, no hood around suctorial mouth, branchial swelling lost, prominent eyes, two separate dorsal fins; trunk silver laterally, iridescent blue dorsally; 120 mm.; catadromous to sea. Macrophthalmia — juvenile. Form eel-like, with expanded suctorial mouth, eye present, male with prominent pouch ventrally on head; colour when leaving the sea similar to macrophthalmia, becoming dull grey; anadromous from sea to breed; N.Z.-wide; 55 cm., adult). (Fig. 1.)

F. Retropinnidae — smelts, cucumbers or silveries.

Small, slender, silvery fishes, usually with a purplish lateral sheen and a cucumber-like smell; pelvic fins abdominal. The males have larger fins than the females and in some species have small nuptial tubercles on the latero-ventral trunk and the lower fins. Seven species occur in New Zealand, some of these being migratory estuarine forms, the others lake dwelling. There are two genera, Retropinna and Stokellia.

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F. Aplochitonidae — ‘Grayling’.

F. Galaxiidae — includes whitebait, kokopu and mudfishes.

Mostly small, scaleless fishes with thick fleshy fins, rounded trunks and sometimes quite stout build. The sexes are similar and the colouration generally sombre. They are usually solitary, secretive, fast-swimming fishes. Five species have marine juveniles (whitebait) which migrate upstream from the sea in the late winter and spring in mixed-species shoals.

(Fig. 5.). (slender, pectoral fin lateral; pale with darker mottling, silver belly; shoaling; lowland streams; N.Z.-wide; juvenile, marine whitebait; 160 mm.)

Canines strongly developed; gill rakers long, caudal fin slightly concave, fins thick and fleshy   G. fasciatus Gray

(similar to N. apoda but much darker in colour; north of North Island; small holes in peat swamps, sometimes swamp creeks; 120 mm.)

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F. Pleuronectidae — flounders.

One species commonly found above tidal estuaries; genus Rhombosolea. R. retiaria Hutton

(Fig. 4.). (rounded outline with blunt snout; grey-brown to black on right side with many brick red blotches, each surrounded by a dark halo, left side grey to yellowish-brown; estuaries and upstream; quiet muddy pools to rapid gravelly rivers, also lowland lakes; N.Z.-wide; juvenile probably marine; 75 cm.)

F. Anguillidae — fresh-water eels.

Two species occur in New Zealand, one growing to large size; apparently scaleless but possessing small scales embedded in skin. The pelvic fins are absent; genus Anguilla.

Dorsal fin extends much further forward along the body than anal fin, vomerine teeth in a narrow band, cleft of jaw extends past eye A. dieffenbachi Gray

(features gross, thick lips, broad bulbous head, especially in large examples; dark dorsally, yellowish-brown ventrally, estuaries to upland lakes and streams; N.Z.-wide; juvenile marine; 180 cm.)

Dorsal fin extends only a little in advance of anal fin, vomerine teeth in a club-shaped mass, cleft of jaw just reaches eye A. australis schmidti Phillipps

(Fig. 3.). (features more slender; greenish-brown to grey dorsally, grey-white ventrally; estuaries, lowland streams and lakes; N.Z.-wide; juvenile marine; 90 cm.)

F. Eleotridae — bullies.

These are mostly small fishes with large scales, thoracic pelvic fins and two dorsal fins. The sexes are dimorphic, the male being more brightly coloured than the female, having larger fins, stouter build and growing larger than the female; two genera are recognised — Philypnodon and Gobiomorphus.

(Fig. 14.). (fairly stout, depressed and ventrally flattened, under-shot jaw, fins large and fleshy, pelvic fins jugular; light grey with several oblique irregular dark bands across trunk, fins and belly reddish; mostly in swift often unstable gravel rivers; N.Z.-wide; juvenile probably marine; 175 mm.).

Acknowledgements