Care
The Watchman Goby is known from the sandy/rubbly margins of coastal reefs, lagoons, and seagrass beds to depths of 20m (66ft). Here, these fascinating bottom dwellers occur either singly or in pairs, and may be observed industriously sifting mouthfuls of sand in order to feed on the small invertebrates, organic matter, and algae contained within. A large mature reef aquarium with a deep sand bed and a well-established refugium are essential for this species. Watchman Gobies like to dig burrows underneath rocks and coral bases, so be sure that any structures are secure, and that there is a good depth of (live) sand in most parts of the aquarium. This will not only enable them to create a burrow, but is also a vital lifeline for them as they sift through this substrate in their ongoing search for tiny food items. The sand is taken in through the mouth, the food items swallowed, and the remaining sand is expelled through the gills. These fish are not overly particular where they dump the sand they have sifted, and as it is usually expelled whilst the fish are in motion, it can sometimes end up dropping down onto and swamping prized corals. For this reason, they are not always a welcome addition to aquaria containing delicate coral life, and careful planning is needed. However, if their requirements can be met, it must be said that these fish do a remarkably good job of overturning the substrate and keeping it looking fresh. The Watchman Goby can be a rather territorial towards conspecifics, so it is best maintained singly, unless a compatible male-female pair can be acquired. Tankmates should be of similar size and peaceful temperament. Avoid housing alongside dottybacks and hawkfishes, which may behave rather pugnaciously towards these gobies. Capable of jumping from open aquaria, so do ensure that the tank has tight fitting covers. May also be seen on sale as the Brownbarred Goby or Whitebarred Goby.
Feeding
This species gains the vast majority of its food through sifting the contents of large established sand beds for tiny invertebrates and algae, and may starve to death in tanks without a mature, live sand substrate. The diet should also be supplemented with small sized meaty frozen foods such as Mysis shrimp and Spirulina/vitamin-enriched brineshrimp, along with herbivore rations. Offer small amounts of food several times per day, target feeding if necessary.
Breeding
In the wild, these fish form monogamous pairs, and the onset of spawning is synchronous with semi-lunar phases. This species has spawned in the home aquarium, but raising the microscopic larvae is extremely challenging. The male will construct a suitable burrow and will entice the female to spawn inside. Once the egg mass has been laid/fertilised, the male drives off the female and guards the cave until the eggs hatch, which is usually at around 72-96 hours (temperature dependent). The resultant larvae are just under 3mm in length and will require feedings of miniscule foodstuffs such as live rotifers. It is unlikely that the young will survive the attentions of the other fish in a community reef set-up.
