---
title: Oblique-Banded Cardinalfish (Apogon semiornatus)
scientific_name: Apogon semiornatus
common_name: Oblique-Banded Cardinalfish
taxon: Cardinals
conservation_status: LC - Least Concern
published: 2024-11-08T11:00:28.174Z
updated: 2026-08-15T13:38:58.929Z
tags: Oblique-Banded Cardinalfish, Apogon semiornatus, Cardinals, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/fishes/bony-fishes/cardinals/oblique-banded-cardinalfish
---

# Oblique-Banded Cardinalfish (*Apogon semiornatus*)

## Quick facts

- **Group:** Cardinals (*Apogonidae*)
- **Size:** up to 8 cm
- **Depth:** 5-30 m
- **Diet:** Carnivore
- **Activity:** Nocturnal
- **Rarity:** Uncommon
- **Habitat:** Caves, overhangs and rubble on reef slopes
- **Reproduction:** Mouthbrooder, Gonochoric
- **Conservation status:** LC - Least Concern

## How to recognise it

- pale pink body with two dark oblique bands running down and back
- one band through the eye, the second across the middle of the body
- deep in caves and undercuts, usually alone
- length up to 8 cm

A small pink cardinalfish with two dark diagonal bands, hanging in a cave or an undercut and usually on its own.

Oblique bands are unusual on this family - most of the group runs its stripes lengthwise - and they do a different job. A diagonal breaks the horizontal line of a fish, which is the shape a predator looks for, and against the confused shadows of a cave interior it works better than a stripe would.

It lives deeper in cover than most cardinalfish, and it hunts small crustaceans in the dark just outside its hole rather than joining the nightly movement over open bottom.

Eight centimeters (3 in), pink in torchlight and effectively black without one - red and pink read as dark at depth, which is why so many cave and night fish are that color. It is a mouthbrooder like the rest of the family.

## Also known as

- **English:** obliquebanded cardinalfish, Oblique-banded Cardinalfish, Half-band Cardinalfish
- **Portuguese:** Cardeal-obliquo
- **Czech:** parmovec křivopruhý
- **Japanese:** ヤミテンジクダイ, Yamitenjikudai
- **Chinese:** 半飾天竺鯛, 大目側仔, 大面側仔

## Scientific synonyms

- *Amia diencaea* Smith & Radcliffe, 1912
- *Amia semiornata* (Peters, 1876)
- *Apogon diencaeus* (Smith & Radcliffe, 1912)
- *Apogon warreni* Regan, 1908

## Range

Comoros, Indian Ocean, Madagascar, Mozambique, Seychelles, South Africa

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*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/fishes/bony-fishes/cardinals/oblique-banded-cardinalfish)*
*Updated: August 15, 2026*