Valenciennea sexguttata (Chalk Goby / Sixspot Goby / Sleeper Blue Dot Goby)
• Small fish safe: ✅ Yes
• Small invert safe: ⚠ With caution (may consume very small ornamental shrimp)
• Coral safe: ✅ Yes
• Minimum tank size: 200L+ (preferably with a mature, deep sand bed)
• Adult size: ~14 cm (5.5 inches)
• Diet: Carnivorous (primarily feeds on small invertebrates within the sand; may accept live foods and, with acclimation, frozen or prepared foods)
• Be aware of: Requires a well-established aquarium with a deep, fine sand substrate for burrowing and feeding. Prone to starvation if adequate natural food sources are not available. May be territorial towards conspecifics unless kept as a mated pair. Prone to jumping, so a secure lid is essential.
Chalk Goby (Valenciennea sexguttata) – A Diligent Sand-Sifting Reef Fish
The Chalk Goby, also known as the Sixspot Goby or Sleeper Blue Dot Goby, is a vibrant and active speciescelebrated for its sand-sifting behavior and striking appearance. This goby plays a beneficial role in maintaining aquarium substrate health, making it a favored choice among marine aquarists.
Appearance and Coloration
The Chalk Goby is distinguished by:
• A sleek, elongated body with a predominantly white to pale gray coloration.
• Six distinctive blue spots along its flanks, contributing to its common name.
• Bright blue markings under the eyes and mouth, adding to its visual appeal.
• A maximum length of approximately 14 cm (5.5 inches).
These features make the Chalk Goby a visually appealing addition to marine aquariums.
Natural Habitat and Behavior
Native to the Indian Ocean and western Pacific Ocean, the Chalk Goby inhabits bays and lagoons with silt or sand substrates and larger pieces of rock under which it burrows. In the wild, they are often observed:
• Sifting through sandy or silty substrates in search of small invertebrates.
• Creating burrows beneath rocks or coral rubble for shelter.
• Living in small aggregations, displaying social behavior.
In captivity, replicating these environmental conditions is crucial for their well-being.
Tank Requirements and Water Parameters
To thrive, Chalk Gobies require specific tank conditions:
• Minimum tank size: 200 liters (50 gallons) to provide ample space.
• Substrate: A deep (at least 5 cm), fine sand bed to facilitate natural burrowing and feeding behaviors.
• Aquascape: Stable rock structures to prevent collapse due to burrowing activities.
• Water parameters:
• Temperature: 23–27°C (73–81°F)
• pH: 8.1–8.4
• Salinity: Specific gravity of 1.020–1.025
A well-established aquarium with a mature sand bed rich in microfauna is essential to support their natural feeding habits.
Diet and Feeding
Chalk Gobies are carnivorous sand sifters, primarily feeding on small invertebrates within the substrate. In captivity:
• Natural feeding: They sift sand through their mouths, extracting edible organisms and expelling the sand through their gills.
• Supplemental feeding: Offer small, vitamin-enriched meaty frozen foods to ensure adequate nutrition.
Without a mature sand bed teeming with microfauna, they are prone to starvation. Regular monitoring of their body condition is essential.
Compatibility and Tank Mates
Chalk Gobies are generally peaceful but have specific compatibility considerations:
• Suitable companions: Other peaceful, non-aggressive fish that do not compete for the same food resources.
• Invertebrates: Caution is advised, as they may consume very small ornamental shrimp.
Avoid housing with:
• Aggressive or territorial species that may intimidate or outcompete them.
• Other sand-sifting gobies, unless the tank is large enough to prevent territorial disputes.
If keeping a pair, ensure they are a mated pair to prevent aggression.
Breeding and Reproduction
Breeding Chalk Gobies in captivity is rare and not well-documented. In the wild:
• Spawning occurs within burrows, with the female staying in the burrow with the eggs until they hatch, while the male guards the entrance.
Due to the complexity of their breeding behaviors, successful captive breeding is uncommon.
Health and Disease Considerations
Chalk Gobies are susceptible to common marine diseases, often exacerbated by stress or poor nutrition:
• Malnutrition: Due to their specialized feeding habits, they are at high risk of starvation if not provided with adequate natural food sources.
• Parasitic infections: Stress and poor water quality can make them more susceptible to parasites.
To maintain their health:
• Provide a well-established tank with a mature sand bed.
• Offer a varied diet with natural live food sources.
• Ensure stable water parameters with good filtration.