TankBud

Green clown goby

Gobiodon histrio

Also known as Broad-barred Goby, Green Coral Goby, Earspot Coral Goby

SaltwaterFish

Green clown goby (Gobiodon histrio)
Bjoertvedt · CC BY-SA 3.0

Care at a glance

Temperature
72–79°F
22–26°C
pH
8.1–8.4
Adult size
1.8 in
4.5 cm
Minimum tank
11 gal
40 L
Temperament
Peaceful
Social behavior
Social
Swim level
Bottom
Diet
Carnivore
Difficulty
Easy
Breeding
Substrate spawner · Medium
Rarity
Very common
Reef safe
Reef safe with caution
Family
Gobiidae
Origin
Indo-West Pacific reefs, from the Red Sea to Samoa, north to southern Japan and south to the Great Barrier Reef

Overview

The green clown goby is a small, peaceful goby that spends its life around one coral head in a reef tank. It is easy to keep.

Did you know

A green clown goby almost never leaves its home coral head. Moved elsewhere in the same tank, it will often work its way back across the rock to the exact branch it called home.

Caring for the green clown goby

Give green clown gobies a mature reef tank of at least 11 gal (40 L), with calm flow. They need a branching coral or sturdy rock perch nearby, not open swimming room or a sand bed. Keep the water at 72 to 79°F (22 to 26°C), with a pH of 8.1 to 8.4.

Green clown gobies rate reef safe with caution, since they do not eat coral as food. A pair defending its home coral can nip at the polyps and tips of SPS such as Acropora, though. Egg laying on the underside of a branch can also leave localized tissue damage.

The risk stays low in a well-stocked reef with several coral colonies to spread across. In an LPS or soft coral tank with no SPS to perch on, it is close to a non-issue.

Feed small meaty foods such as mysis and enriched brine shrimp a few times a day. A green clown goby does not travel far to find its own food.

Green clown gobies are peaceful and rarely bother tank mates. Two unpaired fish will squabble if forced to share a small tank, though. Breeding them is moderately difficult.

Good to know

The green clown goby is a small coral goby in the family Gobiidae. Its pale to olive green body is marked by thin orange stripes on the head. It has no swim bladder and rests directly on its perch, propped on pelvic fins fused into a sucker-like disc. Its skin secretes a bitter, mildly toxic mucus that discourages predators. That is likely why such a small, slow fish can sit out in the open on a reef with little cover. Pairs are protogynous hermaphrodites and can change sex to match a new partner.

In the wild

The green clown goby lives on Indo-West Pacific reefs from the Red Sea to Samoa. Its range reaches north to southern Japan and south to the Great Barrier Reef. It perches directly on the branches of stony corals, especially Acropora, and rarely strays more than a body length from its host head. Pairs will often stay on the same coral colony for months, using its branches as both home and lookout post.

Symbiotic relationships

Clown gobies and their Acropora

Clown gobies spend their lives wedged in the branches of Acropora corals, eating the coral's mucus and the small animals that live on it. Their skin carries a toxin that puts off predators, so the coral becomes a safe house. The coral is paid back in a way nobody expected: when a toxic seaweed touches an Acropora, the coral releases a chemical signal within minutes, and the gobies swim out and trim the seaweed back. Corals with gobies lose far less tissue to seaweed than corals without them.

A clown goby wants a branching coral to sit in, and Acropora is the natural choice, though it will settle for other branching stony corals. It is tiny, peaceful and needs small food several times a day. The one caution is the coral itself: a pair may nip a patch of Acropora or Montipora bare to lay eggs on the skeleton, and a small colony can lose a branch that way. Keep one, or a pair, per tank; two males fight.

Every symbiotic relationship in the catalog

Weekly picks

Tank mates

The green clown goby is a peaceful, social species that keeps to the bottom. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

What size tank does a green clown goby need?

A green clown goby needs at least 11 gal (40 L). It spends most of its time in the bottom.

What temperature and pH does a green clown goby need?

A green clown goby is comfortable at 72–79°F (22–26°C) with a pH of 8.1–8.4.

What does a green clown goby eat?

A green clown goby eats small meaty foods such as mysis and enriched brine shrimp. Feed it a few times a day, since it does not travel far to find food.

How big does a green clown goby get?

An adult green clown goby reaches about 1.8 in (4.5 cm).

How does a green clown goby breed?

Green clown gobies lay their eggs on the underside of a coral branch, and a pair defends its home coral. Breeding them is moderately difficult.

Related species