Citron Goby

Geographical Origin and Habitat: Indo-Pacific: widely distributed from the Red Sea and East African coast to Samoa, north to southern Japan and south to the Great Barrier Reef. It inhabits lagoons and protected outer coral reefs, living exclusively in association with branching hard corals of the genus Acropora.

Taxonomy and Morphology: Belongs to the family Gobiidae, genus Gobiodon. Features a laterally compressed body, lacking scales and covered by a protective toxic mucus. It reaches a maximum size of about 6.5 centimeters in adulthood. Displays a large, rounded head with small eyes and fleshy lips.

Social Behavior: Lives in small groups or pairs among the branches of Acropora. It is a stationary benthic fish that rarely moves from its host coral. It defends its coral from other specimens of the same species. It produces a toxic skin mucus with an unpleasant taste to deter predators.

Coloration and Sexual Dimorphism: Characterized by a uniform bright lemon-yellow or yellowish coloration. Displays four thin vertical iridescent blue-light blue lines on the head (around the eye and on the operculum) and two longitudinal blue lines at the base of the dorsal and anal fins. There is no visible sexual dimorphism.

Aquarium Setup: Requires a nano reef type aquarium starting from 50-60 liters. The presence of branching hard corals, preferably live Acropora or hard coral skeletons, is fundamental, serving as a natural den and perch for the fish. The bottom can be sandy or rocky.

Diet and Feeding: Carnivorous. In nature, it feeds on small benthic invertebrates, zooplankton, and sometimes the mucous tissue of the host coral. In the aquarium, it accepts small-sized frozen foods (brine shrimp, minced mysis, copepods) and small dry granular foods fed near its coral.

Water Quality: Requires stable parameters typical of coral reefs: temperature between 24 and 27 °C, pH between 8.1 and 8.4, and density at 1.020-1.025. To preserve the health of the associated live corals and the fish itself, excellent water filtration with regular water changes is necessary.

Compatibility and Cohabitation: Very peaceful with fish of other families. Can be housed with calm and non-aggressive species (such as clownfish, pipefish, other small gobies). It may occasionally nip or cause minor damage to the polyps of live Acropora corals where it perches and lays eggs.

Aquarium Breeding: Bidirectional hermaphroditic species. Spawning typically occurs on the branches of the host coral, where the pair scrapes a small portion of tissue to adhere the eggs. The male guards the clutch. Hatching and weaning of the larvae are complex.

Risks and Diseases: It is a hardy fish thanks to the protection of the toxic skin mucus that defends it from many external parasites. The main risk is starvation due to lack of feeding if tankmates are too active and fast to consume food, scaring it away.