How to Identify Murray River Rainbowfish

To identify Murray River Rainbowfish (Melanotaenia fluviatilis), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Males are typically more brightly colored than females, especially during breeding. They exhibit iridescent scales ranging from silvery-blue to greenish-yellow, often with a prominent reddish or orange stripe running horizontally along the mid-lateral line. Fins can be reddish or yellowish, sometimes with dark margins. Females are generally duller, with a more subdued silvery-grey body and less intense fin coloration. Crimson spots may be present on the scales, particularly in males.

Scale type

cycloid

Mouth position

superior

Distinctive features

Two dorsal fins, the first much smaller than the second, Laterally compressed body, Relatively large eyes, Prominent mid-lateral stripe (especially in males)

Dorsal fin

Two dorsal fins; the first is small with 3-7 spines, the second is larger with 1 spine and 8-14 soft rays. The origin of the second dorsal fin is typically posterior to the origin of the anal fin.

Tail fin

Forked caudal fin.

Pectoral fin

Pectoral fins are relatively small and positioned high on the body.

Distinctive fins

Anal fin is long, originating anterior to the second dorsal fin, with 1 spine and 15-22 soft rays. Pelvic fins are small and located abdominally.

Identification Tips

1. 1

   Body Shape and Size

   Elongated, laterally compressed body, typically reaching a maximum standard length of 8-10 cm, though some individuals may reach up to 12 cm.

2. 2

   Coloration

   Look for iridescent silvery-blue to greenish-yellow body, often with a distinct reddish or orange mid-lateral stripe. Males are more vibrant, especially during breeding, and may display crimson spots on scales. Females are duller.

3. 3

   Fin Configuration

   Note the two dorsal fins, with the second being significantly larger than the first. The anal fin is long and originates anterior to the second dorsal fin. The caudal fin is forked.

4. 4

   Mouth Position

   The mouth is superior, indicating a feeding habit that often involves surface or mid-water prey.

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