Madagascar Rainbow

Madagascar RainbowDistribution Known only from small streams and the lower reaches of rivers, most of which drain into a series of coastal lagoons and lakes in Atsinanana region, eastern Madagascar. Although the extent of its historical range is unclear, modern distribution extends southwards from the lower Ivoloina River, just north of Toamasina city, as far as Manambalo Creek which lies south of the town of Vatomandry. The lakes and rivers along this stretch of

Distribution

Known only from small streams and the lower reaches of rivers, most of which drain into a series of coastal lagoons and lakes in Atsinanana region, eastern Madagascar. Although the extent of its historical range is unclear, modern distribution extends southwards from the lower Ivoloina River, just north of Toamasina city, as far as Manambalo Creek which lies south of the town of Vatomandry.

The lakes and rivers along this stretch of coastline are connected by the Canal des Pangalanes, an artificial waterway constructed to allow boat transport throughout the natural lake system. It’s the longest man-made canal in the world, extending for some 600 km.

South of Manambalo Creek and in the middle and upper Ivoloina River this species is replaced by undescribed members of the genus,  in middle and upper sections of rivers within the boundaries of its range by B. leucopteron, and north of the Ivoloina by B. longianalis.

Habitat

Inhabits clear, flowing streams at altitudes up to 30 m AMSL, and shows a preference for habitats partially or completely shaded by riparian vegetation where water flow is not too strong. All habitats are characterised by extremely soft freshwater, and it has also been collected from blackwater swamp habitats with low pH and tannin-stained water. In unshaded or turbid environments it’s replaced by introduced Gambusia holbrooki and Xiphophorus maculatus.

Young specimens have been observed to congregate in shallow, marginal zones with adults preferring deeper water, and is normally found in groups of ‘up to several dozen’ (Loiselle and Rodriguez, 2007). The species is also fished for food across the majority of its range.

Maximum Standard Length

80 – 100 mm.

Water Conditions

Temperature: A range of 23 – 32 °C has been recorded in its natural waters during a single month.

pH: 4.5 – 7.5. Wild specimens are likely to require more acidic water then farmed fish.

Hardness: 0 – 268 ppm