Diamond Watchman Goby
Valenciennea puellaris
Tireless sand-sifter that keeps the substrate cleanIntermediate
- Lifespan
- 4-6 years
- Size
- 13-15cm (5-6in)
- Social needs
- Solitary or a bonded pair
- Time
- Medium
- Cost
- Medium
- Diet
- Carnivore, sand-dwelling micro-invertebrates
Overview
What is this animal?
- The Diamond Watchman Goby is a pale, orange-spotted sand-sifter that constantly scoops mouthfuls of substrate to filter out food, keeping the sandbed clean and aerated.
- It is attractive, peaceful, and endlessly busy.
- It is rated intermediate because, like other sifting gobies, it depends on a mature sandbed rich in microfauna and can slowly starve in sterile tanks.
- A deep sandbed and supplemental feeding are essential.
Temperament
- Peaceful and reef-safe, it ignores corals and other fish, spending its time sifting and excavating burrows under rocks.
- It rarely bothers tankmates and is bullied only by very aggressive fish.
- Keep singly or as a bonded male-female pair, as two unpaired individuals may quarrel.
- Its burrowing can undermine rockwork, so build a stable aquascape on the bare bottom rather than on the sand.
A good fit for
- Reef keepers wanting a clean sandbed
- Tanks with a deep, mature sandbed
- Keepers who will supplement feedings
- Peaceful community and reef systems
Common mistakes to avoid
- Starves in sterile or shallow sandbeds
- Sifting dusts corals and shifts rockwork
- Known jumper; needs a secure lid
- Two unpaired gobies may fight
Enclosure
Minimum 110 litres (29 US gallons)
Fine alone or with company. Solitary or a bonded pair
- Provide a tank of at least 110L (30 gallons) with a deep, fine sandbed it can sift and burrow in, plus live rock for shelter.
- A mature sandbed populated with micro-invertebrates supports its natural feeding.
- Keep temperature 24-27C (75-81F), salinity 1.024-1.026, pH 8.1-8.4, and ammonia and nitrite at zero.
- Its constant sifting can dust corals and shift aquascaping, so anchor rockwork securely.
Supplies
Setup
- Tank, stand and sump
- Return pump and powerheads
- Protein skimmer
- Reef lighting
- Rock and sand
- Salt mix, refractometer and test kits
- Quarantine tank
Ongoing
- Frozen mysis shrimp
- Frozen enriched brine shrimp
- Frozen cyclops
- Micro marine pellets
- Copepod bottle or refugium culture
- Turkey baster or pipette for target-feeding
- Small thawing cup and fine strainer
Safe substrate: Aragonite sand · Dry or cured live rock · Bare bottom
Care routine
Daily
- Check salinity, temperature and flow
- Check the lid and every gap
- Feed
- Head-count and look everyone over
- Top up evaporation with fresh water
Weekly
- Service the skimmer and filter socksevery 3 days
- Clean the glass
- Test the water
Monthly
- Water changeevery 2 weeks
- Calibrate the refractometer
- Check salt, RO/DI and reagents
- Replenish sand-bed life
Less often
- Deep-clean pumps and powerheadsevery 3 months
- Replace RO/DI filter mediaevery 6 months
Vet: Quarterly review with a lid check — every 3 months
Top resources for more info
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Diet
- A carnivore that sifts sand for copepods, worms, and other tiny invertebrates throughout the day.
- As it depletes the sandbed's fauna, supplement with frozen mysis, brine shrimp, and sinking carnivore foods.
- Many sifting gobies slowly waste away in tanks without enough sandbed life, so target-feeding and a deep, living sandbed are important.
- A rounded belly confirms it is getting enough food.
Health
- Reasonably hardy once feeding, but starvation in a depleted sandbed is the leading cause of decline.
- Quarantine new fish, keep water stable, and confirm the goby is eating before relying on natural sifting.
- Watch the belly profile and energy: a thin, listless fish needs more supplemental food.
- It is also a jumper, so a secure lid prevents a common and avoidable loss.
Is your enclosure big enough?
Is this urgent?
In a reef, stability matters more than any single target number. A parameter moving fast does more damage than a parameter sitting slightly off.
Go now
Today
Quarantine every new animal, including corals and inverts. It is the single practice that separates a reef that lasts from a reef that restarts.
This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.
What it really costs
Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.
Bedding and substrate
In a marine system the rock and the sand are life support, and how you start them decides the first six months.
Safe
With a caveat
Never
This is our general list for saltwater fish. We have not built one specific to Gobies yet.
My kit says 0.25 ppm. Is that dangerous?
A liquid kit measures total ammonia, but only the un-ionised fraction is really toxic, and that fraction is governed by pH and temperature — each whole pH unit multiplies it roughly tenfold. So the same reading can be nearly harmless in one tank and lethal in another; this works out which one you are in.
Compare with other animals
The same axes for every animal, side by side — the way the guides are written makes that a fair comparison rather than two articles.
Gobies, side by side
Same axes, same care guides — the honest way to choose between types.
See all Gobies side by side →
