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Contents
Overview
The splendid rainbowfish (Melanotaenia splendida) is a species with several subspecies spread across northern and eastern Australia and southern New Guinea. The one most often sold is the eastern form (M. s. splendida), with a silvery green body, scales that shimmer blue and green, thin reddish stripes, and red- or yellow-edged fins in males.
It's one of the toughest rainbows: in the wild it handles swings in temperature and water chemistry that many fish can't, which makes it very forgiving for beginners. Its appeal is in the group: a school of males flaring their fins in a long tank is striking. It does grow fairly large, though, and needs room.
Care and tank setup
At 4-4.7 in (10-12 cm) as an adult and full of energy, it needs about 55 gallons (200 L) and a 4-foot (120 cm) tank for a group. It's tolerant of water conditions (slightly acidic to alkaline, soft to hard) but appreciates stability, solid filtration and regular water changes.
- Keep 6 or more, with at least two females per male.
- Hardy plants around the edges, driftwood and a large open area in the middle.
- Moderate flow and a lid: it jumps readily.
It's peaceful with similar-sized fish: other rainbows, robust barbs, giant danios, corydoras, plecos and calm cichlids. It may eat very small fish, fry and dwarf shrimp, and its constant motion stresses slow fish. A frequent mistake is treating it as a small community fish because juveniles are 1.2-1.6 in in the store. Never release it into the wild; outside its native range it harms local species.
Feeding
An undemanding omnivore. In the wild it eats insects that fall on the water, small crustaceans and algae. At home, feed a quality pellet or flake with spirulina and add brine shrimp, mysis, bloodworms and daphnia, frozen or live. It feeds at the surface and in midwater; split the ration into two small meals a day.
Breeding
It's an easy spawner. A pair lays a few sticky eggs daily on fine plants or a yarn mop for several weeks, especially with slightly warmer water and plenty of live food. The parents don't guard the eggs and will eat them, so move the mop to another container. Fry hatch in 7-10 days and start on infusoria, then baby brine shrimp.
Compatible tank mates
Species from our database that share water parameters, size and temperament with the Eastern rainbowfish (splendid rainbowfish). Calculated from the data in each profile.
Bristlenose pleco Ancistrus sp. 26 gal (100 L) · 72–81 °F (22–27 °C) 
Betta fish Betta splendens 7 gal (25 L) · 75–82 °F (24–28 °C) 
Bronze cory Corydoras aeneus 21 gal (80 L) · 72–81 °F (22–27 °C) 
Zebra danio Danio rerio 16 gal (60 L) · 64–77 °F (18–25 °C) 
Guppy Poecilia reticulata 14 gal (54 L) · 72–82 °F (22–28 °C) 
Cherry barb Puntius titteya 16 gal (60 L) · 73–81 °F (23–27 °C) 
Tiger barb Puntigrus tetrazona 26 gal (100 L) · 72–79 °F (22–26 °C) 
Nerite snail Neritina natalensis 5 gal (20 L) · 72–82 °F (22–28 °C) 
Horned nerite snail Clithon corona 5 gal (20 L) · 72–82 °F (22–28 °C) 
Common goldfish Carassius auratus 79 gal (300 L) · 50–75 °F (10–24 °C) 
Panda cory Corydoras panda 16 gal (60 L) · 68–77 °F (20–25 °C) 
Dwarf gourami Trichogaster lalius 16 gal (60 L) · 75–82 °F (24–28 °C) Check the compatibility of your whole tank →
What not to keep it with
Popular species you shouldn’t house with the Eastern rainbowfish (splendid rainbowfish), and why.
- Oscar: one may eat the other due to size, incompatible temperaments
- Celestial pearl danio: one may eat the other due to size
- Ember tetra: one may eat the other due to size
- Amano shrimp: eats shrimp
- Cherry shrimp: eats shrimp
Recommended equipment
What you need to keep the Eastern rainbowfish (splendid rainbowfish) healthy, checked against Amazon stock.
Frequently asked questions
How many liters does a Eastern rainbowfish (splendid rainbowfish) need?
At least about 200 liters for a group of at least 6 fish. More space always helps keep the water stable.
What water temperature does the Eastern rainbowfish (splendid rainbowfish) need?
Between 22 and 28 °C, with a pH of 6.5 to 8.
What fish can live with the Eastern rainbowfish (splendid rainbowfish)?
Based on water, size and temperament, it fits with species such as Bristlenose pleco, Betta fish, Bronze cory, Zebra danio and Guppy. Use our compatibility calculator to check your whole tank.
Can the Eastern rainbowfish (splendid rainbowfish) be kept with shrimp?
Not recommended: because of its size or instinct, it will eat shrimp.
