How to Identify Upside-down Catfish

To identify Upside-down Catfish (Synodontis nigriventris), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

The body is typically mottled brown to dark grey, with irregular darker spots or blotches. The most distinctive feature is its counter-shaded coloration, where the ventral (belly) side is darker than the dorsal (back) side, an adaptation for its upside-down swimming habit. This is known as reverse countershading.

Scale type

none

Mouth position

inferior

Distinctive features

Inverted swimming posture, Reverse countershading (darker belly, lighter back), Three pairs of barbels around the mouth, Adipose fin present, Strong, serrated spines in dorsal and pectoral fins

Dorsal fin

Single dorsal fin with a strong, serrated spine and 7 soft rays.

Tail fin

Forked caudal fin.

Pectoral fin

Pectoral fins with a strong, serrated spine and soft rays.

Distinctive fins

Adipose fin is present and relatively small.

Identification Tips

1. 1

   Swimming Posture

   The most obvious identifier is its tendency to swim upside down, especially when feeding or resting.

2. 2

   Coloration

   Observe the reverse countershading: the belly is darker than the back, which is unusual for most fish.

3. 3

   Size

   Adults typically reach a maximum standard length of 9.5 cm (3.7 inches), making them relatively small for a Synodontis species.

4. 4

   Barbels

   Presence of three pairs of barbels around the mouth, which are used for sensing food in murky waters.

Explore Upside-down Catfish