Factsheet native murray-darling rainbowfish · This fish fact sheet is an extract derived from the...
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66 FISHES OF THE MURRAY-DARLING BASIN Identification A small, strongly laterally compressed fish, the adults of which have a relatively deep body. Maximum length 90 mm, commonly less than 70 mm. e eyes are large and positioned towards the top of the head, and the mouth is moderately large, oblique and upturned, with several rows of small, conical teeth. ere are two dorsal fins separated by a small gap, with the first short-based and the second long-based. ere is a long-based anal fin and the tail is moderately forked. ere is no lateral line and the scales are relatively large. Colouration varies with sex, age and habitat, but is generally silvery with a greenish iridescence and whitish on the lower head and belly. Younger individuals are translucent. e majority of scales have a brownish margin. ere is a pink to-reddish spot on the operculum. Males have red spots on the dorsal, caudal and anal fins, and the fins of breeding males have a blackish margin. Females and immatures have clear fins. Biology and Habitat Rainbowfish are a tropical to sub-tropical group, and Murray-Darling rainbowfish is the southern-most species in the group. e species is generally found in the lowland parts of the Basin, and prefers slow-flowing rivers, wetlands and billabongs. It is a schooling species—schools of 30 or more are commonly seen swimming just below the water surface. Breeding is seasonal, generally spring-summer when water temperature exceeds 20°C, and males perform an elaborate courtship display. Fecundity is low (average 130 eggs, range 35– 333) with females laying 5–20 eggs per batch, in 3–4 batches per day for several days. e eggs sink and lodge amongst aquatic plants, where they attach via adhesive threads. Eggs are 1.3–1.8 mm diameter, and hatch after about 1 week, with the larvae ~2.0–3.7 mm long. Individuals mature at 10–12 months old. Until recently it was not known that this species migrated, but individuals as small as 21 mm have been recorded moving through a fishway on the Murrumbidgee River, most commonly in the afternoon and dusk. Common Name Murray-Darling rainbowfish (Crimson-spotted rainbowfish, Murray River rainbowfish) Uncommon Scientific Name Melanotaenia fluviatilis (Castelnau, 1878) NATIVE SPECIES Photo: Gunther Schmida Male in breeding colouration
Transcript of Factsheet native murray-darling rainbowfish · This fish fact sheet is an extract derived from the...
F i s h e s o F t h e M u r r ay- Da r l i n g B a s i n 67An introductory guide66 F i s h e s o F t h e M u r r ay- Da r l i n g B a s i n 67An introductory guide6666 F i s h e s o F t h e M u r r ay- Da r l i n g B a s i n
identificationA small, strongly laterally compressed fish, the adults of which have a relatively deep body. Maximum length 90 mm, commonly less than 70 mm. The eyes are large and positioned towards the top of the head, and the mouth is moderately large, oblique and upturned, with several rows of small, conical teeth. There are two dorsal fins separated by a small gap, with the first short-based and the second long-based. There is a long-based anal fin and the tail is moderately forked. There is no lateral line and the scales are relatively large. Colouration varies with sex, age and habitat, but is generally silvery with a greenish iridescence and whitish on the lower head and belly. Younger individuals are translucent. The majority of scales have a brownish margin. There is a pink to-reddish spot on the operculum. Males have red spots on the dorsal, caudal and anal fins, and the fins of breeding males have a blackish margin. Females and immatures have clear fins.
Biology and habitatRainbowfish are a tropical to sub-tropical group, and Murray-Darling rainbowfish is the southern-most species in the group. The species is generally found in the lowland parts of the Basin, and prefers slow-flowing rivers, wetlands and billabongs. It is a schooling species—schools of 30 or more are commonly seen swimming just below the water surface. Breeding is seasonal, generally spring-summer when water temperature exceeds 20°C, and males perform an elaborate courtship display. Fecundity is low (average 130 eggs, range 35–333) with females laying 5–20 eggs per batch, in 3–4 batches per day for several days. The eggs sink and lodge amongst aquatic plants, where they attach via adhesive threads. Eggs are 1.3–1.8 mm diameter, and hatch after about 1 week, with the larvae ~2.0–3.7 mm long. Individuals mature at 10–12 months old. Until recently it was not known that this species migrated, but individuals as small as 21 mm have been recorded moving through a fishway on the Murrumbidgee River, most commonly in the afternoon and dusk.
Common name Murray-darling rainbowfish (crimson-spotted rainbowfish, Murray river rainbowfish)
uncommon
scientific name Melanotaenia fluviatilis (castelnau, 1878)
natiVe sPeCies
Phot
o: G
unth
er S
chm
ida
Male in breeding colouration
F i s h e s o F t h e M u r r ay- Da r l i n g B a s i n 67An introductory guide66 F i s h e s o F t h e M u r r ay- Da r l i n g B a s i n 67An introductory guide66 An introductory guide 67
The species is carnivorous, consuming aquatic invertebrates as well as terrestrial invertebrates that fall on the water surface. Some filamentous algae is also consumed.
Distribution and abundanceFormerly widespread across the Basin, the Murray-Darling rainbowfish has declined in the Murray region, but is still patchily recorded from the middle and lower sections of the Murray, Murrumbidgee and Macquarie rivers, and parts of the Gwydir, Namoi and Bogan rivers in NSW. In Vic, cold winter temperatures limit it to the Murray and its tributaries such as the Goulburn and Broken rivers. The species is not present in the relatively upland ACT, and appears to have disappeared from the Lower Lakes in SA. It is still common but localised/patchy in wetlands and vegetated edges of the main channel of the Lower Murray River in SA and the lower Victorian section below the Darling junction. It appears to be common in the Qld portion of the Basin, but may be confused with the Desert rainbowfish.
Potential threatsPredation of adults by Redfin perch and larvae by Eastern gambusia are considered potential threats, as are loss of aquatic vegetation (spawning sites and cover) and cold-water pollution.
general referencesBackhouse & Frusher 1980; Baumgartner 2003; Cadwallader & Backhouse 1983; Humphries et al. 2002; Koehn & O’Connor 1990; Lloyd & Walker 1986; McGuigan et al. 2000; Milton & Arthington 1984; Moffat & Voller 2002; Wedderburn & Hammer 2003.
iD VALLey 1 Avoca 2 Border rivers 3 Broken 4 campaspe 5 castlereagh 6 central Murray 7 condamine 8 darling 9 goulburn 10 gwydir 11 Kiewa 12 Lachlan 13 Loddon 14 Lower Murray 15 Macquarie 16 Mitta Mitta 17 Murrumbidgee 18 namoi 19 ovens 20 Paroo 21 upper Murray 22 Warrego 23 Wimmera
Published by the Murray-Darling Basin Commission Postal address: GPO Box 409, Canberra ACT 2601 Office location: Level 3, 51 Allara Street, Canberra City ACT Telephone: (02) 6279 0100, international + 61 2 6279 0100 Facsimile: (02) 6248 8053, international + 61 2 6248 8053 Email: [email protected] Internet: http://www.mdbc.gov.au
For further information contact the Murray-Darling Basin Commission office on (02) 6279 0100
This fish fact sheet is an extract derived from the report: Lintermans, M. 2007, Fishes of the Murray-Darling Basin: An introductory guide.
MDBC Publication No. 10/07
ISBN 1 921257 20 2
© Murray-Darling Basin Commission 2007
This work is copyright. Graphical and textual information in the work (with the exception of photographs, artwork and the MDBC logo) may be stored, retrieved and reproduced in whole or in part provided the information is not sold or used for commercial benefit and its source (Fishes of the Murray-Darling Basin) is acknowledged. Such reproduction includes fair dealing for the purpose of private study, research, criticism or review as permitted under the Copyright Act 1968. Reproduction for other purposes is prohibited without the permission of the Murray-Darling Basin Commission or the individual photographers and artists with whom copyright applies.
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