Exquisite sand-goby

Where they come from

Exquisite sand-gobies (Favonigobius exquisitus) are little bottom-dwellers from coastal Australia. Think sandy flats, tidal creeks, and estuaries where the salinity swings around with rain and tides. They are built for that life: bury, dart, hunt tiny critters, repeat.

Setting up their tank

These gobies live on (and in) the sand. Give them a footprint more than height. A 20 gallon long is a nice starting point for a small group, and bigger is always easier with brackish fish.

• Tank size: 20 gallon long minimum for a group, 30-40 is more relaxed
• Substrate: fine sand, deep enough to bury (I aim for 2-3 inches)
• Hardscape: a few smooth rocks, shells, and bits of driftwood for breaks in line-of-sight
• Plants: go for brackish-tolerant stuff (Java fern tied to wood, Anubias, or mangrove-style roots). Many true plants melt at higher salinity
• Flow/filtration: decent turnover with gentle areas. Sponge prefilter helps because they explore everywhere
• Cover: tight lid. Gobies can pop up fast if spooked

For salinity, I keep them in low-to-mid brackish. The exact number depends on your stock list, but something like SG 1.005-1.010 is a realistic range for long-term keeping. Mix saltwater with marine salt (not table salt) and measure with a refractometer if you can. Swing-arm hydrometers can be pretty sloppy in this range.

Temperature-wise, normal tropical range works well (low-to-mid 70s F is comfortable). Give them plenty of oxygenation. Warm, brackish water can run low on dissolved oxygen faster than you expect.

What to feed them

They are hunters. Mine ignored flakes for a while and acted like I was pranking them. Once they learn prepared foods, life gets easier, but you will still get the best results with meaty, sinking stuff.

• Best staples: frozen mysis, frozen brine (enriched if possible), chopped krill, finely chopped clam
• Great small foods: live or frozen cyclops, daphnia (if they will take it), baby brine shrimp for smaller specimens
• Prepared: sinking micro pellets for carnivores, Repashy-style gel foods pressed onto the sand
• Frequency: small meals 1-2 times daily, especially at first

I like target-feeding with a turkey baster or pipette. Squirt a little cloud of food right onto the sand in front of them. They will figure it out quickly, and you will waste less food into the filter.

How they behave and who they get along with

Exquisite sand-gobies are classic sand-sitters with quick bursts of speed. They perch, bury, and hop along the bottom. They are not murderous, but they are confident around their own kind and will bicker over favorite spots.

• Keep singly or in a small group if the tank has enough bottom space
• Expect harmless squabbles: fin flares, short chases, posturing
• Most active at feeding time and in lower light

Tankmates should be brackish and not too pushy. Avoid anything that will treat them like snacks, and avoid hyperactive fish that will outcompete them for food.

• Good general matches: small brackish hardy fish like bumblebee gobies (if salinity overlaps), knight gobies (with caution), mollies, monos or scats only if the tank is large and you can keep everyone fed
• Use caution: puffers (many will nip), larger gobies, big hungry predators, or anything that patrols the bottom nonstop
• Avoid: large cichlids, big archerfish in small tanks, aggressive crabs that grab resting fish

Breeding tips

Breeding is possible, but it is not a freebie like livebearers. They are substrate spawners and like to use caves, shells, or little undercuts. If you want to try, the biggest trick is getting a compatible pair and keeping them well-fed without letting water quality slide.

• Offer multiple spawning sites: small caves, half shells, short sections of PVC tucked under wood
• Keep salinity steady and the tank calm. They get picky if things swing around
• Condition with live/frozen foods and feed a bit heavier while doing extra water changes
• If you see a male guarding a spot and chasing others off, you might be close

Common problems to watch for

Most issues I have seen with sand-gobies come down to three things: salinity swings, not eating enough, and sand bed gunk.

• Not eating: new imports can be shy or picky. Start with live/frozen and target-feed
• Rapid breathing or hanging at the surface: check oxygenation, temperature, and ammonia/nitrite first
• Frayed fins: often from sparring or nippy tankmates, sometimes from poor water
• White spot/ich lookalikes: brackish changes the treatment playbook, and some meds behave differently in salt. Quarantine helps a lot
• Sunken belly: usually competition or parasites. If feeding is solid and they still waste away, consider deworming in quarantine

Sand beds can trap waste. I do light surface siphoning during water changes, not deep vacuuming that turns the whole bed over. Let the gobies do their digging, and you just keep the top tidy and keep up with water changes.