How to Identify Rainbowfishes

To identify Rainbowfishes (Melanotaeniidae), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Highly variable, ranging from iridescent blues, greens, reds, oranges, and yellows. Males are typically more brightly colored than females, especially during breeding. Many species exhibit horizontal stripes or blotches.

Scale type

cycloid

Mouth position

superior

Distinctive features

Two distinct dorsal fins, the first being smaller and spiny, the second larger and soft-rayed., Laterally compressed body., Relatively small, upturned mouth., Often exhibit a 'hump' on the forehead in older males of some species.

Dorsal fin

Two dorsal fins; the first is short with 3-7 spines, the second is longer with 6-22 soft rays. The second dorsal fin is often elongated in males.

Tail fin

Forked or emarginate caudal fin.

Pectoral fin

Moderately sized, typically clear or slightly colored.

Distinctive fins

Pelvic fins are thoracic, located beneath or slightly behind the pectoral fins. Anal fin is long, originating near the middle of the body and extending to the caudal peduncle.

Identification Tips

1. 1

   Body Shape

   Look for a laterally compressed, somewhat elongated body with a distinct arch to the back, especially in males.

2. 2

   Dorsal Fins

   Observe the two distinct dorsal fins; the first is small and spiny, followed by a larger, soft-rayed second dorsal fin. The gap between them can vary.

3. 3

   Coloration

   Note the vibrant, often iridescent colors, which can change intensity based on mood, health, and breeding status. Males are generally more colorful.

4. 4

   Mouth Position

   Their small, upturned mouth is characteristic, indicating a feeding preference for surface or mid-water prey.

Explore Rainbowfishes