Pinafore goby

Where they come from

Pinafore gobies (Drombus simulus) are little marine sand-and-rubble gobies from shallow coastal areas. Think calm lagoons, sheltered flats, and patchy reef edges where there is fine sand, broken shell, and bits of rubble to duck into. They are built for living low to the ground and letting food come to them.

Setting up their tank

These gobies are advanced mostly because they do best in a mature, stable marine tank with lots of micro-life. You can keep them alive in a newer setup, but keeping weight on them long term is the real challenge.

• Tank size: I would start at 20 gallons for one, bigger if you want a small group or more bottom fish.
• Mature system: 6+ months old is my comfort zone, with visible pods and a "lived in" sandbed.
• Sandbed: fine sand, about 2-3 inches. Too coarse and they will not sift comfortably.
• Rubble and hides: small piles of rubble, shells, and a couple low caves. They like quick cover right next to where they feed.
• Flow: moderate overall, but give them a few calmer pockets near the bottom so they are not constantly blasted.
• Filtration: solid skimming and mechanical filtration helps because you will feed heavier than you think.
• Lid: they can hop, especially when startled. Cover gaps.

Standard reef parameters work. Stability matters more than chasing a magic number. Big swings in salinity or temperature will show up as hiding, not eating, and slow fading over a week or two.

What to feed them

Pinafore gobies are small-mouth, pick-and-sift feeders. In my experience, the ones that fail are the ones that never really transition to prepared foods, or they do but still do not get enough calories.

• Best starters: live baby brine (enriched), live copepods, live blackworms (rinsed well) if you can get them safely for marine use.
• Frozen that usually works: mysis (small), calanus, cyclops, finely chopped brine, roe/eggs, "reef plankton" blends.
• Prepared: some learn to take tiny pellets or granules, but do not count on it at first.

Feed small amounts 2-4 times a day at the beginning. They do much better with frequent little hits than one big dump. I use a pipette and put food right on the sand near their perch so the clownfish and wrasses do not steal everything in the water column.

How they behave and who they get along with

They are peaceful, a bit shy, and very routine-driven. Once settled, they will perch, hop between a few favorite spots, and sift sand or pick at the surface all day. Sudden movement outside the tank, a big fish cruising by, or a hand in the water can send them straight into hiding.

• Good tankmates: small, calm fish that are not hyper-competitive at feeding time (firefish, small assessors, gentle blennies, tiny cardinals).
• Risky tankmates: fast eaters (many wrasses, dottybacks), pushy clowns in small tanks, hawkfish, larger basslets.
• Avoid: predators and anything that views tiny gobies as snacks (lionfish, bigger groupers, some large coral crouchers), and bully bottom fish.

With other gobies, it depends. Similar tiny sand gobies can work in larger tanks with multiple hiding zones, but in smaller setups one will usually claim the prime corner and the other will sulk. If you try a pair or group, add them together and build extra cover so they can establish separate "parking spots".

Breeding tips

Captive breeding is possible with a lot of gobies, but with Drombus simulus it is not something most hobbyists stumble into. If you do end up with a bonded pair, you may see them sharing a burrow and doing little courtship hops near the entrance.

• Give them options: a couple tight caves and a few half-buried shells or small rubble tunnels.
• Feed heavy and varied: conditioning is all about frequent small meaty foods and a steady pod population.
• Keep things calm: a busy tank full of fast fish will shut down any nesting behavior.

Common problems to watch for

Most issues come back to three things: not eating enough, stress from tankmates, and instability in a newer system.

• Slow starvation: the fish pecks all day but still gets thinner. Fix with target feeding, more frequent meals, and reducing competition.
• Getting outcompeted at feeding time: you are feeding enough, but the food never reaches the bottom. Use a pipette and feed after lights dim a bit.
• Hiding for days: often a sign of bullying or sudden parameter swing. Check salinity, temp, and watch interactions.
• Jumping: common after a scare. Cover the tank and keep a calm zone with easy cover.
• Sandbed too coarse or too shallow: you will see less natural sifting and more skittishness. Fine sand and a bit of depth helps.

If you set the tank up for them (mature sandbed, calm bottom zone, and a plan to feed small foods often), they are really rewarding. They are not flashy, but they have tons of personality once they decide your tank is safe.