How to Identify Gertrude's Rainbowfish

To identify Gertrude's Rainbowfish (Pseudomugil gertrudae), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Males are typically iridescent blue to yellow-orange, often with a yellowish belly. They possess numerous small, dark spots on their body and fins. Females are generally duller, with a more translucent body and fewer, less prominent spots. The eyes are often a striking blue.

Scale type

cycloid

Mouth position

superior

Distinctive features

Small size, typically reaching 3-4 cm (1.2-1.6 inches) in total length., Prominent black spots on the body and fins, especially noticeable on the caudal, dorsal, and anal fins., Elongated, often filamentous rays on the dorsal and anal fins of mature males., Bright blue irises.

Dorsal fin

Two dorsal fins; the first is small with 4-7 spines, the second is larger with 1 spine and 5-8 soft rays. Males have elongated rays on the second dorsal fin.

Tail fin

Forked caudal fin, often with black spots.

Pectoral fin

Small and transparent, positioned high on the body.

Distinctive fins

Anal fin with 1 spine and 8-12 soft rays, often elongated in males. Pelvic fins are small.

Identification Tips

1. 1

   Size and Shape

   Small, slender body, rarely exceeding 4 cm. Look for the characteristic elongated body typical of Pseudomugil species.

2. 2

   Coloration and Spots

   The most definitive feature is the presence of numerous small, dark (often black) spots scattered across the body and fins, particularly prominent on the caudal, dorsal, and anal fins. Males exhibit more vibrant iridescent blue or yellow hues.

3. 3

   Fin Morphology (Males)

   Mature males have noticeably elongated rays on their second dorsal and anal fins, giving them a 'spiky' appearance. This is a key differentiator from females and some other Pseudomugil species.

4. 4

   Eye Color

   The bright blue iris is a common and attractive feature, though not exclusive to this species.

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