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Care guide · Freshwater · fish

Madagascar rainbowfish

Bedotia madagascariensis

Young pair of Madagascar rainbowfish (Bedotia madagascariensis)
Image: Loiselle & Rodriguez, CC BY 3.0; resized and converted to JPEG. Photo: Paul V. Loiselle and Damaris Rodriguez · Source · CC BY 3.0resize-convert-compress

The Madagascar rainbowfish (Bedotia madagascariensis) is an active, silver-blue shoaling fish from eastern Madagascar. It needs generous swimming room and is often mislabelled as Bedotia geayi in the aquarium trade. Buy only fish whose identity and source are as clear as possible. Keep at least eight to ten in a long, mature aquarium with open swimming lanes, shade and cover. The species is listed as Endangered and reacts poorly to abrupt changes in water or surroundings. Ask about the source line and check after feeding that smaller fish get enough. A calm routine and stable maintenance matter more than quick adjustments.

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At a glance

Temperature
23–32 °C
pH
4.5–7.5
GH
0–15 °dGH
Aquarium length
At least 120 cm
Minimum aquarium volume
At least 108 L
Adult size
Up to 10 cm
Group size
At least 8 individuals
Temperament
Peaceful

About this species

The accepted scientific name is Bedotia madagascariensis Regan, 1903, family Bedotiidae. Do not use the frequent misspelling madagascarensis. Loiselle and Rodriguez redescribed this species and B. geayi in 2007. The fish is slender and shimmering with dark lateral stripes; adult males are more colourful and have more ornate unpaired fins. Females are fuller-bodied. Seriously Fish reports up to 10 cm standard length, while FishBase gives a somewhat lower maximum in its cited data. Plan space using the larger specialist value.

Natural habitat

This species is endemic to eastern Madagascar and inhabits clear, shaded streams and lower river reaches. Wild habitats and populations are vulnerable. B. geayi has long been incorrectly applied to fish in the aquarium trade; taxonomic literature indicates many such fish are B. madagascariensis. A shop label or photograph is not always enough evidence. Prefer traceable captive-bred stock and never release aquarium fish outdoors.

Aquarium and layout

Seriously Fish recommends considering a long tank with a footprint of about 120 × 30 cm, roughly 108 litres gross, as a minimum. It swims actively; juvenile shop fish do not remain small enough to justify a tiny aquarium. Keep at least eight to ten together. Leave wide swimming lanes but provide shaded, planted margins and wood. Good filtration, oxygenation and regular water care are essential. Use a secure lid because active Bedotia can jump. Acclimate new fish slowly.

Water conditions

The specialist care profile gives broad tolerance ranges of 23–32 °C, pH 4.5–7.5 and GH 0–15 dGH. These are not values to target simultaneously. Keep the conditions of the established stock stable and avoid abrupt changes. Natural streams may be soft and acidic. Added salt is unnecessary. The reviewed sources do not establish a separate KH target.

Behaviour and group size

The Madagascar rainbowfish is non-aggressive and naturally shoaling, but it is active and may outcompete much smaller or slower tankmates at feeding time. Keep at least eight to ten conspecifics. Choose companions of similar adult size, swimming speed and water needs. Avoid predators and avoid housing with other Bedotia species because hybridisation is possible. Due to historic confusion with B. geayi, accurate identification matters. Compatibility also depends on space and feeding style, not just water values.

Feeding

In nature it feeds mainly on terrestrial insects and other invertebrates. Offer quality dried flakes or granules sized for its mouth, supplemented with small live or frozen prey such as Daphnia, Artemia and bloodworm. Variety matters; dry food alone is not an ideal full menu. Give measured portions that the shoal can finish without polluting the water. Remove leftovers, especially for juveniles or in a temporary smaller tank.

Breeding

The fish scatters adhesive eggs among vegetation or on a spawning mop. Java moss and fine-leaved plants can be used as spawning media. Spawning may continue for several days. In a confined breeding tank males may pursue females persistently; provide cover and monitor their condition. Adults may eat eggs. Check plants or mops regularly and move eggs if raising fry separately. Seriously Fish reports hatching in about 7–10 days. Fry first need infusoria-sized foods, then Artemia nauplii. Keep water very stable because young fish are sensitive to abrupt changes.

Sources & review

This care guide draws on several specialist sources and was last checked on .

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