---
title: False Decorated Goniobranchus (Goniobranchus pseudodecorus)
scientific_name: Goniobranchus pseudodecorus
common_name: False Decorated Goniobranchus
taxon: Nudibranch
published: 2026-08-24T11:00:27.244Z
updated: 2026-08-24T13:16:03.477Z
tags: False Decorated Goniobranchus, Goniobranchus pseudodecorus, Nudibranch, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/molluscs/nudibranch/false-decorated-goniobranchus
---

# False Decorated Goniobranchus (*Goniobranchus pseudodecorus*)

## Quick facts

- **Group:** Nudibranch (*Nudibranchia*)
- **Size:** up to 1.6 cm
- **Diet:** Spongivore
- **Activity:** Diurnal
- **Rarity:** Rare
- **Habitat:** Sponge-covered rubble and reef
- **Reproduction:** Simultaneous hermaphrodite, Egg layer
- **Hazard:** Poisonous
- **Endemic:** Endemic to the Red Sea

## How to recognise it

- orange margin with white patches breaking it
- very small, under 2 cm, which is most of why it is missed
- found in the Red Sea and nowhere else
- up to 1.6 cm

The name says what happened: somebody had already used decorus for another slug, this one looks like it, and it is not it.

That is the ordinary condition of this genus. Species separated by a band width and a spot count were lumped for decades under whichever name was published first, and the revisions of the last ten years have been pulling them apart again, which is why so many recent names begin with pseudo or end in a person. This one was described in 2018 from Red Sea material and is known from this sea alone.

At sixteen millimeters it is the smallest chromodorid in this catalogue, and the size is most of the reason nobody photographs it. An orange margin broken by white patches is unmistakable at close range and invisible from half a meter away, which on a reef means it is passed over by everybody who is not specifically hunting slugs.

Everything else is standard for the family: it feeds on sponges, keeps the sponge's defensive chemistry and concentrates it in the rim of the mantle, and therefore does not run, does not hide and does not react much to a light.

If you photograph a small orange-rimmed slug in this sea, the picture is worth keeping and dating. This is a species with very few records, and most of what is known about where it lives comes from a handful of divers who happened to look closely at the right piece of rubble.

## Also known as

- **Russian:** Гониобранхус ложноукрашенный

## Range

Egyptian part of the Red Sea, Saudi Arabia

---

*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/molluscs/nudibranch/false-decorated-goniobranchus)*
*Updated: August 24, 2026*