The Black-ray goby, also known as the Filament-finned prawn-goby, is a saltwater fish that is well-suited for home aquariums. With their distinctive black and yellow markings and interesting behavior, these small fish make an attractive addition to any marine tank. In this article, we will explore the size and appearance, region, behavior, diet, and how to keep Black-ray gobies in a home aquarium.
Black-ray gobies typically grow to a length of 8-10 centimeters (3-4 inches) in the wild, but can be slightly smaller in captivity (5 centimeters / 2 inches). They have a slender body with a black and white pattern and distinctive yellow colored forehead, with the black coloration appearing in stripes along their body. The fins are typically transparent. Males are usually slightly smaller than females.
The Black-ray goby is found in the western Pacific, particularly in the waters around Indonesia, the Philippines, and Papua New Guinea. They are commonly found living in symbiosis with pistol shrimp, sharing a burrow together.
Black-ray gobies are peaceful and relatively easy to care for. They are active during the day and enjoy burrowing in the substrate. They are also known to form a symbiotic relationship with pistol shrimp (Alpheus randalli) in the wild, in which the shrimp digs a burrow and the goby helps to maintain the burrow by moving sand and debris. Be careful at home because they are known to jump out of the aquarium.
In the wild, Black-ray gobies primarily feed on small crustaceans and other invertebrates found in the sand and substrate. In captivity, they can be fed a variety of foods, including frozen or live brine shrimp, Mysis shrimp, and krill. It is also recommended to supplement their diet with high-quality pellets or flakes designed for marine fish.
Keeping Black-ray gobies at home
To keep Black-ray gobies healthy and happy in a home aquarium, it is important to provide them with an appropriate environment. An ideal candidate for a nano tank where you can observe the interesting behavior of the symbiotic relationship it forms with the pistol shrimp. But we recommend to go for a tank with at least a tank size of 75 liters (20 gallons), to give them plenty of room to swim and burrow. It’s also easier to keep the water parameters stable. The tank should have a sand substrate and plenty of live rock for the fish to explore and hide in.
Water parameters are also important to monitor. The ideal water temperature for Black-ray gobies is between 22-26 °C (72-79 °F) and the pH should be kept between 8.1-8.4.
It is also important to keep in mind that Black-ray gobies are social fish that enjoy the company of their own species, you can keep them as a pair. They can be kept with other peaceful fish in a community tank, but should be kept with other gobies or pistol shrimp to maintain their symbiotic relationship.
Black-ray gobies are a popular and interesting addition for a marine aquarium. With their striking appearance and interesting behaviors, they are sure to be a hit with any fish enthusiast. By providing them with an appropriate environment and diet, they can live for up to 5 years in captivity, giving you plenty of time to enjoy their company.
|Type of aquarium
|Reef aquarium / Nano reef aquarium
|Up to 5 centimeters / 2 inches in captivity
|Indo-Pacific region, from the Maldives to Fiji
|Ideal tank size
|75 liters / 20 gallons or more
|Ideal water temperature
|23-27 °C / 73-81 °F
|8.1 – 8.4
|Carnivorous, primarily feed on small crustaceans and other invertebrates
|Egg layers, males guard the eggs until they hatch
|Up to 5 years in captivity
|Often kept in pairs, can be kept with other small gobies and fish species.