Identity and search names

Common name
Murray River rainbowfish
Scientific name
Melanotaenia fluviatilis
Other names
Murray River rainbowfish, Australian rainbowfish, Melanotaenia fluviatilis
Category
Freshwater fish
Group
Rainbowfish and blue-eyes
Origin
Murray–Darling Basin rivers, wetlands and connected waters of south-eastern Australia
Review outcome
PASSED

Environment and housing

Environment
Freshwater
Care level
Beginner to intermediate
Adult size
Usually 8–11 cm total length
Expected lifespan
About 5–8 years
Minimum housing
At least 240 L with a 150 cm swimming length for a group of eight or more
Temperature
14–26 °C with seasonal tolerance; avoid chronic excessive warmth
pH
6.5–8.2
Hardness or minerals
Moderately soft to hard
Salinity
Freshwater
Lighting
Moderate to bright with planted margins
Social structure
Keep at least eight, preferably ten or more, with a balanced sex ratio
Placement or swimming zone
Upper and middle water
Temperament
Peaceful, fast-swimming and highly social
Compatibility
Use active peaceful fish that tolerate cooler Australian freshwater conditions and can compete safely at feeding time
Habitat structure
Long well-oxygenated aquarium with open swimming room, planted margins, secure lid and seasonally appropriate temperature

Feeding and nutrition

Diet
Aquatic and terrestrial insects, crustaceans, algae and balanced omnivore prepared foods
Feeding frequency
Feed small varied portions once or twice daily and prevent fast adults from excluding smaller fish

Breeding and reproduction

Breeding or reproduction
Adults deposit adhesive eggs among fine plants or spawning mops over multiple days. Move mops or eggs to a separate rearing container to prevent predation
Parental care
No parental care; adults may consume eggs and fry

System demands

Filtration
Use mature biological filtration sized for the full adult group and feeding load, with intake protection where juveniles, long fins or small fish are present. Provide steady turnover without preventing normal swimming or resting.
Aeration
Maintain strong surface gas exchange and stable dissolved oxygen. Increase aeration during warm weather, medication, transport recovery, breeding crowding or any ammonia or nitrite event.
Maintenance
Test ammonia, nitrite and nitrate, remove waste from feeding and shelter zones, and perform regular temperature- and chemistry-matched water changes before nitrate or dissolved organics accumulate.

Detailed husbandry

Identity scope
This profile applies to the Australian native Melanotaenia fluviatilis. It must not be confused with the closely related eastern rainbowfish M. duboulayi, and wild collection or translocation requires current legal authority.
Adult size and space
Usually 8–11 cm total length. At least 240 L with a 150 cm swimming length for a group of eight or more. Plan around adult dimensions, activity, social structure, aggression and waste production rather than sale size.
Social structure
Keep at least eight, preferably ten or more, with a balanced sex ratio
Placement or swimming zone
Primary zone: Upper and middle water. Keep that zone usable for movement, feeding and refuge.
Feeding ecology
Aquatic and terrestrial insects, crustaceans, algae and balanced omnivore prepared foods
Feeding plan
Feed small varied portions once or twice daily and prevent fast adults from excluding smaller fish
Water stability
Maintain 14–26 °C with seasonal tolerance; avoid chronic excessive warmth; pH 6.5–8.2; hardness/minerals: Moderately soft to hard. Stable oxygenation and nitrogen-cycle control matter more than chasing one exact number.
Adult projected load
Plan capacity for Keep at least eight, preferably ten or more, with a balanced sex ratio at the documented adult size (Usually 8–11 cm total length) in At least 240 L with a 150 cm swimming length for a group of eight or more. Include feeding intensity, territorial behaviour and breeding growth rather than counting sale-size juveniles.
Filtration
Use mature biological filtration sized for the full adult group and feeding load, with intake protection where juveniles, long fins or small fish are present. Provide steady turnover without preventing normal swimming or resting.
Aeration
Maintain strong surface gas exchange and stable dissolved oxygen. Increase aeration during warm weather, medication, transport recovery, breeding crowding or any ammonia or nitrite event.
Maintenance
Test ammonia, nitrite and nitrate, remove waste from feeding and shelter zones, and perform regular temperature- and chemistry-matched water changes before nitrate or dissolved organics accumulate.
Habitat structure
Long well-oxygenated aquarium with open swimming room, planted margins, secure lid and seasonally appropriate temperature
Compatibility plan
Use active peaceful fish that tolerate cooler Australian freshwater conditions and can compete safely at feeding time
Breeding plan
Adults deposit adhesive eggs among fine plants or spawning mops over multiple days. Move mops or eggs to a separate rearing container to prevent predation Parental care: No parental care; adults may consume eggs and fry.
Quarantine
Quarantine new fish in a separate cycled aquarium with dedicated equipment. Match temperature and mineral chemistry gradually, confirm feeding and normal respiration, and never add transport water to the established aquarium.
Welfare checks
Maintain the stated adult space and social structure, verify feeding and intervene early when injury, exclusion, weight loss, abnormal respiration or altered behaviour appears. Australian native status does not permit casual collection, movement or release. Check state rules and preserve the origin of captive lines.
Biosecurity and release
Never release fish, fry, eggs, aquarium water, sediment, plants or live foods into drains, dams or natural waterways. Confirm current Australian import conditions and South Australian possession, trade and movement rules before acquisition or transfer.
Main risk
Australian native status does not permit casual collection, movement or release. Check state rules and preserve the origin of captive lines.
Overridable warnings
Australian native status does not permit casual collection, movement or release. Check state rules and preserve the origin of captive lines. Any override must still preserve adult space, social welfare, stable chemistry, oxygen and filter capacity.

Welfare and risk

Welfare checks
Maintain the stated adult space and social structure, verify feeding and intervene early when injury, exclusion, weight loss, abnormal respiration or altered behaviour appears. Australian native status does not permit casual collection, movement or release. Check state rules and preserve the origin of captive lines.
Main warning
Australian native status does not permit casual collection, movement or release. Check state rules and preserve the origin of captive lines.
Biosecurity
Never release fish, fry, eggs, aquarium water, sediment, plants or live foods into drains, dams or natural waterways. Confirm current Australian import conditions and South Australian possession, trade and movement rules before acquisition or transfer.

Sources

Source note

Current identity or scope, husbandry, system-demand, welfare and Australian biosecurity evidence checked; active retired-source links removed; all AquaNexus wording is original.

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