Yellow clown goby

Geographic Origin and Biotope: Widespread in the western Indo-Pacific, from southern Japan down to the Australian Great Barrier Reef. It is an obligate inhabitant of hard coral colonies (especially Acropora), where it lives permanently wedged between the branches.

Taxonomy and Morphology: Yellow Clown Goby. Tiny (max 4 cm / 1.5 inches) and compact, devoid of visible scales. It is equipped with pelvic fins fused to form a small sucker, which allows it to "sit" firmly on corals even in the presence of strong currents.

Social Behavior: Funny, static and lethargic. It almost never "swims" in the classic sense of the term, but hops from branch to branch within its host coral. Very territorial towards conspecifics (it is recommended to introduce only one specimen or an established pair).

Coloration and Sexual Dimorphism: Entirely and brilliantly uniform lemon yellow (sometimes with a very slight white tinge on the cheek). This gaudy (aposematic) coloration warns predators of the toxicity of its skin mucus. Sexual dimorphism visually absent.

Aquarium Setup: Perfect for nano-reefs (even 30 liters / 8 gallons). ABSOLUTE REQUIREMENT: presence of branching SPS corals (Acropora, Montipora digitata, Pocillopora) or, failing that, soft tree corals (Sinularia, Kenya Tree) which it will use as its exclusive home.

Diet and Feeding: Micro-carnivore. Despite being tiny, it is voracious. Often ignores dry food; requires live brine shrimp nauplii, lobster eggs, cyclops and finely chopped mysis, administered in suspension near its coral.

Water Quality: Standard marine parameters: salinity 1.023-1.025, temperature 24-27°C (75-81°F). Being obliged to live in contact with demanding corals (SPS), the water quality must be excellent, with nitrates and phosphates close to zero.

Compatibility and Tankmates: Reef Caution: to clean an area to lay eggs or simply annoyed, it will bite and strip the tissue of Acropora branches, killing small portions. Ignored by large fish thanks to toxic mucus, but perfect with peaceful tankmates.

Aquarium Reproduction: Possible in captivity. They are bi-directional protogynous hermaphrodites (they can change sex in both directions depending on the needs of the pair). They lay circular bands of eggs on coral branches (after having grazed away the polyps).

Risks and Diseases: Extreme sensitivity to copper-based drugs (not having protective scales). The main risk is wasting from starvation in overcrowded tanks with fast eaters who steal their food from the water column.