Giant prawn-goby

Amblyeleotris fontanesii is native to the warm tropical waters of the Western Indo-Pacific. It is found in Indonesia, the Philippines, Singapore, Papua New Guinea, and along the Great Barrier Reef in Australia. It inhabits silty or muddy lagoons and outer reef slopes, preferring sheltered areas with mixed coral rubble and fine sand substrates at depths ranging from 5 to 30 meters.

Belonging to the family Gobiidae, Amblyeleotris fontanesii is recognized as one of the largest members of its genus, reaching a maximum length of up to 25 centimeters as an adult. It features an elongated body, eyes set high on the head for a panoramic view of potential threats, and pelvic fins that are partially fused to help rest on the substrate.

This fish is famous for its mutualistic relationship with snapping shrimps of the genus Alpheus (such as Alpheus bellulus). The shrimp excavates and maintains the burrow, while the goby acts as a sentinel, maintaining physical contact with the shrimp's antennae and warning it of danger with rapid tail flicks.

The coloration of Amblyeleotris fontanesii consists of a beige, grayish, or olive base color marked by three to four broad dark brown or black vertical bands. Small yellow or light blue spots dot the snout and dorsal fins. Sexual dimorphism is minimal; mature metals may show slightly longer dorsal fin filaments and more vivid coloration.

Requires a spacious aquarium of at least 200 liters (approx. 53 gallons) with a deep sand substrate (8 to 10 cm) mixed with small rubble pieces and shell fragments. This thickness is critical to allow the symbiotic Alpheus shrimp to dig its burrow system without collapses. Live rocks must be placed directly on the bottom glass to prevent collapses.

It is a carnivore that feeds on small benthic invertebrates. In an aquarium, it should be fed high-quality frozen foods like mysis, brine shrimp, chopped krill, and lobster eggs. Sinking pellets can also be accepted. Ensure food is dispersed near the burrow entrance, as the goby will rarely venture far from its protective shelter.

Requires stable marine water parameters and efficient filtration. The ideal water temperature is 24°C to 28°C (75°F to 82°F), with pH between 8.1 and 8.4 and a steady specific gravity of 1.021 to 1.025. Nitrate levels should be kept low, and strong water oxygenation is recommended via a protein skimmer and movement pumps.

This is a peaceful species that coexists well with non-aggressive reef fish such as clownfish, pipefish, and small wrasses. Pairing it with a compatible Alpheus snapping shrimp is highly recommended to display its natural behavior. Avoid large predatory fish or aggressive bottom dwellers like large dottybacks.

Spawning in home aquariums is rare and highly complex. The pair spawns inside the burrow constructed by the shrimp, where the male guards the egg clutch. The larvae are planktonic after hatching. Raising them requires specific cultures of live phytoplankton and rotifers, which is challenging for hobbyists.

The primary risk is jumping out of the tank, particularly during the acclimation phase; a secure lid or mesh cover is mandatory. They can contract skin parasites if stressed or if the substrate becomes anaerobic. Keeping the sand clean and monitoring water parameters are key factors in preventing disease.