1. Introduction

Fish are a vital aspect of the waters of the Murray-Darling Basin . They are valued by indigenous people, recreational fisherman and for their values of ecosystem function, conservation and biodiversity. By comparison to elsewhere in the world, the variety of fish found in the rivers of the Murray-Darling Basin is extremely small. There are about 49 fish species having been so far recorded within the rivers, lakes, backwaters, billabongs and estuaries of the Basin (MDBC 2003, SKM 2003). Of these, 11 are introduced species, several are essentially marine or estuarine species found only in the lowest reaches of the Murray , and 9 are diadromous, spending part of their life cycles in freshwater and part in the sea. Only 29 native species complete their life cycles totally within the Murray-Darling River System. The presence of two additional native fish is thought to have resulted from recent introductions to the basin as these fish are not endemic to the system.

There are still many knowledge gaps to be filled about the native and exotic fish of the Basin. For example, arguably our best known freshwater fish, the Murray cod and trout cod were only definitely recognised as separate species in 1972 (Berra & Weatherley 1972). A new species of blackfish was scientifically described in 1984 and research underway now has recognised that additional species of galaxiids and gudgeons exist but await scientific description. As recently as 2002, Yarra pigmy perch were recorded near the Murray Mouth for the first time in the Basin, although Museum samples confirm that the fish was present in the 1980s (Hammer et al. 2002).

Native fish are under significant pressure and populations continue to decline, being subject to a variety of impacts. This decline has seen the development of the Native Fish Strategy for the Murray-Darling Basin 2003-2013, which will guide investment in research, habitat rehabilitation and native fish management into the next decade.

The fish species present in the Murray-Darling Basin are listed in Table 1, with the diagram and map (Figure 1) providing a general indication of their distribution.

Family	Species	Common Name	Status*
Native Fish - Freshwater Species
Ambassidae	Ambassis castelnaui	Western chanda perch	Endangered Populations (NSW)
Atherinidae	Atherinosoma microstoma	Small-mouthed hardyhead
	Craterocephalus amniculus	Darling River hardyhead	Vulnerable (IUCN, ASFB)
	Craterocephalus fl uviatlis	Murray hardyhead	Endangered (IUCN, ASFB, NSW, Vic)
	Craterocephalus stercusmuscarum fl uvus	Fly-specked hardyhead (southern form)
Clupeidae	Nematalosa erebi	Bony bream
Eleotridae	Hypseleotris klunzingeri	Western carp gudgeon
	Hypseleotris spp	Carp gudgeon	several undescribed species exist in this group
	Mogurnda adspersa	Southern Purple-spotted gudgeon	Critically Endangered (Vic)
	Philypnodon grandiceps	Flat-headed gudgeon
	Philypnodon sp.1	Dwarf fl at-headed gudgeon
Gadopsidae	Gadopsis bispinosus	Two-spined blackfish	Vulnerable (ACT)
	Gadopsis marmoratus	River blackfish	Protected (SA)
Galaxiidae	Galaxias fuscus	Barred galaxias	Critically Endangered (IUCN, ASFB, Vic)
	Galaxias olidus	Mountain galaxias
	Galaxias rostratus	Flat-headed galaxias	Vulnerable (IUCN, ASFB)
Kuhliidae	Nannoperca australis	Southern pygmy perch	Protected (SA)
	Nannoperca obscura	Yarra pygmy perch	Vulnerable (IUCN, EPBC, ASFB)
Melanotaenildae	Melanotaenia fl uviatilis	Murray-Darling rainbowfi sh
Percichthyidae	Maccullochella macquariensis	Trout cod	Critically Endangered (Vic)
	Maccullochella peeli peeli	Murray cod	Vulnerable (EPBC)
	Macquaria ambigua	Golden perch
	Macquaria australasica	Macquarie perch	Endangered (ASFB, Vic)
Plotosidae	Neosilurus hyrtlii	Hyrtl’s Tandan
	Tandanus tandanus	Freshwater catfi sh	Protected (SA)
Retropinnidae	Retropinna semoni	Australian smelt
Teraponidae	Bidyanus bidyanus	Silver perch	Critically Endangered (Vic)
	Leiopotherapon unicolor	Spangled perch
Diadromous Species
Anguillidae	Anguilla australis	Short-finned eel
Anguillidae	Anguilla reinhardtii	Long-finned eel
Bovichthyidae	Pseudaphritis urvilli	Tupong
Galaxiidae	Galaxias maculatus	Common galaxias
Galaxiidae	Galaxias brevipinnis	Climbing galaxias	Translocated native
Galaxiidae	Galaxias truttaceous	Spotted galaxias	Translocated native
Geotriidae	Geotria australis	Pouched lamprey
Mordaciidae	Mordacia mordax	Short-headed lamprey
Percichthyidae	Macquaria colonorum	Estuary perch
Introduced Fish
Cobitidae	Misgurnis anguillicaudatus	Weather loach
Cyprinidae	Carassius auratus	Goldfish
	Cyprinus carpio	Carp
	Rutilus rutilus	Roach
	Tinca tinca	Tench
Percidae	Perca fluviatilis	European perch (redfin)
Poeciliidae	Gambusis affnis	Eastern Gambusia
Salmonidae	Oncorhynchus mykiss	Rainbow trout
	Salmo salar	Atlantic salmon
	Salmo trutta	Brown trout
	Salvelinus fontinalis	Brook trout

*Highest conservation rating within Australia
Table 1. Freshwater fish within the MDB (MDBC 2003, SKM 2003)

Figure 2. Murray cod commercial landings in Reach and Lakes and Coorong Fisheries, SA 1951/52 to 1999/2000.