---
title: Spotted Frillgoby (Bathygobius cyclopterus)
scientific_name: Bathygobius cyclopterus
common_name: Spotted Frillgoby
taxon: Gobies
conservation_status: LC - Least Concern
published: 2024-11-20T19:43:59.777Z
updated: 2026-08-25T07:51:23.839Z
tags: Spotted Frillgoby, Bathygobius cyclopterus, Gobies, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/fishes/bony-fishes/gobies/spotted-frillgoby
---

# Spotted Frillgoby (*Bathygobius cyclopterus*)

## Quick facts

- **Group:** Gobies (*Gobiidae*)
- **Size:** up to 7.5 cm
- **Depth:** 0-20 m
- **Diet:** Carnivore
- **Activity:** Cathemeral
- **Rarity:** Uncommon
- **Habitat:** shallow rock and intertidal reef flats
- **Reproduction:** Egg layer
- **Conservation status:** LC - Least Concern

## How to recognise it

- brown, mottled with irregular darker spots
- dark brown saddle under each of the two dorsal fins
- free filament tips on the upper pectoral rays
- rounded tail; females have banded fins, males dusky ones
- up to 7.5 cm

A frillgoby trapped in a tide pool by the falling water does not wait for the sea to come back. It jumps out, over dry rock, into a pool it cannot possibly see from where it started, and it lands in water.

How that works was taken apart in the laboratory on an Atlantic relative, Bathygobius soporator. Fish allowed to swim over the whole rock platform at high water jumped accurately once the tide dropped and left them stranded. Fish denied that swim did not. The animal appears to build a map of the pools while everything is submerged and one continuous space, then use the map hours later when the map is the only thing left. It is a memory of a landscape, held by a fish the length of a finger.

The Red Sea species has not been put through that test. What you can see of it is a small brown fish mottled with darker spots, with a dark brown saddle sitting under each of the two dorsal fins. Females carry banded dorsal and tail fins, males dusky ones. The upper rays of the pectoral fin end in free filaments that stand clear of the fin membrane; that fringe is the frill the genus is named for, and the fish uses it as a set of feelers against rock.

Its habitat is the part of the reef divers skip. Shallow rock, surge channels, intertidal flats, brackish creek mouths, generally in the first meter or two of water even though the species is recorded down to about 20 meters. Its working clock is the tide rather than the sun.

One caution, and it is the guide's own. The regional reference marks its Red Sea photograph of this fish ID tentative. Several Bathygobius look alike in a picture and are separated on pectoral ray structure and scale counts, so treat any sighting here as a probable rather than a certainty.

## Also known as

- **English:** roundfin goby, Spotted Frillgoby, Cyclops Frillgoby
- **Portuguese:** Góbio-ciclope
- **Japanese:** ヤハズハゼ, Yahazuhaze
- **Chinese:** 圓鰭深鰕虎, 圓鰭深鰕虎魚
- **FI:** täpläröyhelötokko

## Scientific synonyms

- *Bathygobius crassiceps* (Jordan & Seale, 1906)
- *Bathygobius laoe* Roxas & Ablan, 1940
- *Bathygobius mearnsi* (Evermann & Seale, 1906)
- *Bathygobius nox* (Bleeker, 1851)
- *Gobius cyclopterus* Valenciennes, 1837
- *Gobius nox* Bleeker, 1851
- *Gobius variabilis* Steindachner, 1901
- *Gobius varius* Steindachner, 1901
- *Mapo crassiceps* Jordan & Seale, 1906
- *Mapo mearnsi* Evermann & Seale, 1906

## Range

Comoros, East Africa, Indian Ocean, Madagascar, Red Sea, Seychelles, South Africa

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*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/fishes/bony-fishes/gobies/spotted-frillgoby)*
*Updated: August 25, 2026*