Violet Goby (Gobioides broussonnetii)

The Violet Goby (Gobioides broussonnetii), also known as the Dragon Goby or Dragon Fish, is a fascinating and unusual species from coastal estuaries, mangrove swamps, and tidal mudflats along the Atlantic coast from the southeastern United States to Brazil. Its long, eel-like body — reaching 50 cm in the wild (typically 30–40 cm in aquariums) — combined with its upward-pointing mouth and iridescent violet-grey coloration create a truly alien appearance.

Despite the fearsome-looking, fang-like teeth and large mouth, the Violet Goby is a gentle filter-feeder and substrate sifter. It feeds by scooping mouthfuls of substrate or water, filtering out small invertebrates, organic particles, algae, and microorganisms. It poses no real threat to fish too large to fit in its mouth.

This species is a brackish-water fish that must have some salt in its water to thrive long-term. It suffers significantly in pure freshwater, developing bacterial infections and deteriorating health over time. A salinity of 1.005–1.015 SG is appropriate.

The Violet Goby is largely nocturnal and spends much of the day buried in substrate or sheltered in caves. A deep, fine-sand substrate is important for their burrowing behavior and prevents injury to their delicate ventral surface.

Water Parameters: Brackish water is ESSENTIAL: salinity 1.005–1.015 SG, pH 7.5–8.5, temperature 22–28°C, GH 15–30. This species cannot thrive long-term in freshwater despite common trade claims. Use marine salt to achieve appropriate salinity. Avoid acidic or very soft water.

Tank Setup: Minimum 200 liters for a single adult due to their eventual size. A DEEP fine sand substrate (10+ cm) is essential for burrowing. Provide caves, PVC pipes, and rocky overhangs for shelter. Subdued lighting. Good filtration that tolerates disturbed substrate from their sifting behavior.

Feeding: Filter-feeder that accepts sinking fine pellets, frozen brine shrimp and mysis (fine), frozen bloodworm, and algae wafers. Sink food directly in front of them or target-feed. May also accept small live foods. Feed daily in small amounts — they have slow metabolisms.

Tankmates: Compatible with other robust brackish species: larger mollies, scats, archerfish, and figure-eight puffers. Avoid freshwater-only fish. Avoid very small fish that may fit in their large mouth. Generally peaceful.

Health: Deteriorates rapidly in freshwater — ensure proper salinity always. Deep substrate prevents skin lesions. Watch for bacterial skin infections, which indicate poor salinity or water quality.