Circus Goby (Priolepis Nocturna) saltwater aquarium fish portrait

The Circus Goby (Priolepis nocturna) is a diminutive, secretive reef dweller from the Indo-West Pacific, reaching roughly an inch and a half in standard length and about three inches at full adult size. Its body is milky white to tan, crossed by four or five broad dark bars over the head and flanks, with a pair of bars running beneath the eye and partly ocellated black spots marking the dorsal and caudal fins. Higher pectoral-fin and scale counts, along with that distinctive barring, separate it from related Priolepis species. In the wild it occupies coral and rocky crevices along reef slopes, drop-offs and lagoons, typically between about 8 and 35 meters.

A 10-gallon aquarium is sufficient for a single adult, provided the layout mirrors the crevice habitat this goby depends on. Build generously with live rock, caves, rubble and narrow fissures so the fish can select a retreat and hold it. A sand or mixed substrate and moderate water movement suit it well, and stable, mature conditions matter more than volume for a fish this small. Because it rarely strays far from shelter, plan the rockwork so that food can be delivered close to its chosen crevice rather than washing past it.

On the reef, this carnivore feeds on tiny benthic invertebrates and zooplankton picked from the surfaces and openings of its crevice habitat. Captive diets should follow that pattern with small meaty items: enriched brine shrimp, mysis, copepods, small zooplankton, and finely chopped fish or shrimp flesh. Appropriately sized carnivore pellets and micro-flakes are accepted as well, though the particle size must be small enough for a fish that measures only a few inches.

Offer modest portions once or twice daily rather than a single heavy feeding. Target food near the rockwork, since this shy goby is easily outcompeted by faster, bolder tankmates and may not venture into open water to chase drifting particles. Spot-feeding with a pipette or turkey baster near its retreat is an effective way to confirm that it is eating.

Mysis Shrimp Enriched Brine Shrimp Copepods Small Zooplankton Finely Chopped Fish Or Shrimp Flesh Small Carnivore Pellets Micro-Flakes
Timid and cryptic, the Circus Goby spends most of its time tucked into coral and rocky crevices and seldom moves far from cover. Wild observations describe it as solitary, and aquarium practice generally favors one specimen per tank, though pairs are sometimes reported to form. Expect long periods out of sight, particularly during the settling-in phase; a well-honeycombed aquascape gives the fish enough confidence to perch at the mouth of its hole and feed.

Pair it with calm, non-aggressive community fishes of similar disposition. Large or pushy species such as groupers, dottybacks, triggerfishes and angelfishes will intimidate, outcompete or simply eat a goby this size and should be excluded. It is coral-safe and well suited to reef systems, and it is reported as safe with most invertebrates, although broader mobile-invertebrate compatibility has not been established with certainty, so observation is worthwhile in tanks housing prized ornamental shrimp or small snails.

FAQ

Frequently Asked Questions

About the Circus Goby

  • Can a Circus Goby live in a nano reef aquarium?
    Yes. A 10-gallon aquarium is adequate for an adult, as long as the system is stable and offers ample rockwork with caves and narrow crevices.
  • What and how often should a Circus Goby be fed?
    Offer small meaty foods such as mysis, enriched brine shrimp, copepods and finely chopped marine flesh once or twice daily. Direct the food toward its hiding area so it is not outcompeted.
  • Is the Circus Goby safe with corals and invertebrates?
    It is coral-safe and well suited to reef aquariums. Safety with most invertebrates is reported, but complete mobile-invertebrate compatibility is not fully established, so monitor tanks with small ornamental shrimp or snails.