Rainford's goby

Where they come from

Rainford's goby (Koumansetta rainfordi) shows up around the Great Barrier Reef and the Coral Sea, hanging out on sandy patches next to rubble and low rock. In the wild they're basically little lawnmowers that stay close to the bottom, picking at microalgae and tiny critters all day.

That background matters because a brand-new, squeaky-clean tank doesn't have much for them to graze on. A mature tank with some "life" on the rocks and sand makes this fish way easier.

Setting up their tank

Think sand, rubble, and lots of little hideouts. Mine spent most of its time doing short hops between caves and the sandbed, then popping out to graze. If your aquascape is all bare rock pillars with no nooks, they tend to stay stressed and invisible.

• Tank size: 20-30 gallons is workable for one, bigger is nicer if you want a busy community
• Sandbed: fine sand helps because they sift and peck constantly
• Rockwork: stable rock with small caves and overhangs right near the sand
• Flow: moderate is fine, but give them calmer pockets near the bottom
• Lighting: whatever your reef runs, but expect them to graze more if you have some algae film and micro growth
• Cover: a lid helps - they can hop, especially if spooked

What to feed them

This is the part that makes them "intermediate." A lot of Rainford's come in skinny, and some ignore big chunky foods at first. Once settled, many will eat frozen readily, but you still want to think of them as constant pickers that do better with frequent small offerings.

• Frozen: mysis (small), brine (better if enriched), finely chopped krill, calanus, copepod blends
• Small meaty: finely chopped clam or shrimp, roe if you can get it
• Prepared: tiny pellets and flakes can work once they recognize food, but don't rely on this at the start
• Natural grazing: pods, microfauna, and algae film on rock and sand

If your tank has fast eaters (wrasses, anthias, clowns that act like piranhas), Rainford's can get outcompeted. I feed a small cloud for the water column fish first, then sneak in a second round right to the bottom for the goby.

How they behave and who they get along with

They're peaceful, a little shy at first, and kind of endearing once they settle in. You'll see them "walk" on the sand and do quick darting runs between cover. Most of the time they're minding their own business, grazing and picking.

• Good tankmates: other peaceful reef fish, small clowns, cardinals, firefish (in calmer tanks), blennies that aren't jerks, most inverts
• Use caution with: boisterous wrasses, dottybacks, hawkfish, and anything that pins them into hiding
• Same species: can fight unless you have a bonded pair and enough space/hiding spots

Reef-safe-wise, mine never bothered corals. They will sit on the sand next to LPS and pick at the ground around them, but they aren't coral nippers in my experience.

Breeding tips

They can spawn in captivity, but raising the babies is the hard part. Adults are cave spawners. If you keep a compatible pair, you'll sometimes notice them sharing a burrow or tight cave and doing a bit of "housekeeping" around it.

• Give them options: small caves and rubble pockets right on the sand
• Keep them well-fed: frequent small meals seems to help conditioning
• If they spawn: eggs are typically guarded in the cave, larvae go pelagic
• Raising fry: you'll need a separate larval setup and live foods (rotifers, then tiny copepods) - not a casual project

Common problems to watch for

• Slow starvation: the big one. They look "fine" until they don't. Watch the belly and the area behind the head for that pinched look.
• Food competition: aggressive eaters steal everything before it reaches the sand.
• New tank syndrome: tanks without pods and algae film make them harder to get established.
• Jumping: especially right after introduction or if chased.
• Ich/velvet sensitivity: like many small reef fish, they can get hit fast if a parasite makes it into the system.

If you can, quarantine and get them eating before they go into the main tank. Not every Rainford's will take pellets on day one, but once they connect "pipette to food" they usually settle into a routine pretty nicely.