Bigeye clingfish
Kopua nuimata
Bigeye clingfish exhibit a slender body with large eyes and a distinctive orange-brown coloration, featuring small dark spots along their sides.
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About the Bigeye clingfish
Kopua nuimata is a tiny deepwater clingfish with big eyes and a neat pink-and-orange banded pattern. It lives way down on reefy slopes (roughly 160-337 m), so its "care" is mostly academic - its natural habitat is cold, dark, high-pressure water that we just do not replicate in home aquariums.
Also known as
Quick Facts
Size
2.7 cm SL
Temperament
Peaceful
Difficulty
Expert
Min Tank Size
20 gallons
Lifespan
unknown
Origin
Southwest Pacific (New Zealand area, Norfolk Ridge)
Diet
Carnivore - likely small crustaceans and other tiny benthic invertebrates
Water Parameters
6-14°C
7.8-8.4
8-12 dGH
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This species needs 6-14°C in a 20 gallon tank. Use our heater calculator to find the right wattage.
Calculate heater sizeCare Notes
- Give it a mature, pod-rich reef tank with lots of tight crevices and overhangs - they spend their life glued under stuff, not cruising the water column.
- Lock your lid down and block weird gaps; they can climb glass and wedge into overflows, and a clingfish in a weir box never ends well.
- Keep salinity stable around 1.025-1.026 and temperature about 24-26 C (75-79 F); they get touchy fast when salinity swings or pH drifts.
- Flow should be moderate with calmer pockets near the rockwork so it can perch and hunt; blasting random flow everywhere just makes it hide and skip meals.
- Feed small meaty foods and feed often: live pods, enriched baby brine, cyclops, chopped mysis, and tiny bits of clam; target feed with a pipette right to its hideout.
- Skip big boisterous fish and anything that outcompetes at feeding time (wrasses, damsels, larger clowns); small, chill gobies and tiny benthic critters are safer tankmates.
- Watch for starvation and pinched belly - they can look 'fine' while slowly losing weight, so check body condition and make sure food actually reaches them.
Compatibility
Good Tankmates
- Small, chill gobies (neon gobies, clown gobies, other tiny perching types). They tend to ignore each other, and the clingfish just does its suction-cup thing on the rockwork.
- Blennies that are more mellow (tailspot blenny style personalities, small rock-perchers). As long as the blenny is not a total hole-hog, they usually coexist fine in a rocky nano setup.
- Firefish and other shy dartfish. They hang in the water column, clingfish stays glued to the rocks, so there is not much overlap or drama.
- Small, peaceful wrasses like a possum wrasse. Good movement without the in-your-face aggression, and they do not usually bother a tiny fish that is sitting on the rock.
- Gentle reef-safe inverts (cleaner shrimp, small hermits, snails). The clingfish is not a bully, and in my experience it mostly just cruises the rock picking at micro stuff.
Avoid
- Big, boisterous wrasses (sixline, melanurus, etc). They are fast, nosy, and can harass or outcompete a clingfish for food, and some will straight-up pick at anything small on the rocks.
- Dottybacks and other scrappy rock-territory fish (orchid dottyback included sometimes). They love the same caves and ledges, and the clingfish loses that argument every time.
- Hawkfish. They perch on the rock and act like little predators, and a tiny clingfish is exactly the kind of snack-sized roommate a hawkfish will test.
Where they come from
Bigeye clingfish (Kopua nuimata) are a little New Zealand oddball. They come from cool-temperate coastal reefs where they spend their life glued to rock and rubble, hiding in cracks and letting the current do the work. If you are used to tropical reef fish that cruise around all day, this one will feel like a different hobby.
If you are thinking "nano fish for a nano reef" - pause. The hard part with clingfish is not space, it is keeping them alive long-term: temperature, micro-foods, and low-stress housing.
Setting up their tank
Build the tank around two things: cool water and lots of places to stick. These fish do not want a wide open scape. They want a maze of rock faces, overhangs, and tight little caves where they can plaster themselves and feel invisible.
Go with an established, mature marine system. New tanks with that "still figuring itself out" swing (film algae one week, cyano the next, parameters bouncing) are rough on them. They are the kind of fish that will look fine right up until they are not.
- Temperature: cool-temperate. Plan on a chiller in most homes (do not assume room temp is safe year-round).
- Flow: moderate, but avoid blasting the exact spots they like to perch. Think strong overall circulation with calmer pockets.
- Rockwork: lots of vertical surfaces and undersides. Flat plates and stacked ledges work great.
- Substrate: sand is fine, but the real "home" is the rock. Keep detritus from building up in dead zones.
- Filtration: oversize it and keep it stable. Skimmer + good mechanical export helps because you will be feeding meaty foods.
Cover every gap. Clingfish can squeeze and they can climb. If there is a slit around a filter, a loose lid corner, or a cable gap, they will eventually find it.
Lighting is more about what you want to keep with them than what they need. They do not care. What they do care about is having shaded perches. I like to build at least a couple of deep, darker "caves" so they always have a low-light option.
What to feed them
This is where most people get humbled. Bigeye clingfish are small-predator pickers. They are not built to chase pellets across the tank, and they often ignore food that is not right in front of their face.
I have had the best luck starting with live foods to get them eating confidently, then transitioning to frozen once they learn the routine. Target feeding is your friend. A long pipette or turkey baster lets you drop food right onto the rock near their perch.
- Best starters: live copepods, live enriched brine, small live mysis (if you can get it), and amphipods from a refugium
- Frozen staples (once they take it): small mysis, finely chopped krill, chopped clam, roe, and high-quality frozen blends
- Feeding style: small amounts, multiple times a day beats one big dump
Teach them a "feeding spot". I use a specific overhang and always squirt food there with pumps briefly turned down. After a week or two, they start being in the right place at the right time.
Watch the belly, not the enthusiasm. A clingfish can look totally calm and still be slowly starving. If the belly looks pinched or the head looks oversized, step up the frequency and offer smaller live prey.
How they behave and who they get along with
They are perch-and-pounce fish. Most of the day you will see a little face and big eyes peeking out, then a quick scoot to a new spot. They are not "centerpiece" fish unless you like hunting for them (I do).
Tankmates are where people accidentally lose them. Anything boisterous, food-competitive, or curious about tiny fish will stress them out or outcompete them at feeding time. Even "reef safe" fish can be a problem just because they are faster and bolder.
- Good ideas: very small, calm, cool-water compatible species that do not hover and peck at rocks all day
- Risky: wrasses, dottybacks, hawkfish, larger gobies/blennies, and basically anything that rushes food
- Inverts: avoid big predatory crabs and large cleaner shrimp that will steal food right off their perch
Skip "cleanup crew" crabs that bulldoze rock and investigate everything. A clingfish relies on staying stuck and unnoticed. Getting pried off a perch by a crab is a bad day.
With other clingfish, I would not assume peace. Some individuals ignore each other, some do not. If you try a pair, do it in a tank with lots of separated perches and be ready with a backup plan.
Breeding tips
Breeding them in captivity is more of a long project than a weekend goal. Like many small benthic marine fish, they are likely to lay eggs in a tucked-away spot and have tiny larvae that need the whole live-food pipeline. If you are not already culturing rotifers and copepods, this is a steep hill.
- If you want to try: keep a stable pair in a species-focused tank with lots of tight caves and minimal disturbance
- Feed heavy on varied small meaty foods to condition them
- Be ready for larval rearing: rotifers first, then copepod nauplii, then larger pods - and you need them available on day one
Even if you never raise larvae, watching for eggs can tell you the fish feel secure. If they never settle in and never claim a hiding spot, something about the setup is off.
Common problems to watch for
Most losses I have seen (and a couple I learned the hard way) come down to three things: temperature creep, slow starvation, and stress from tankmates or handling. They do not always show obvious warning signs.
- Temperature swing or summer heat: they can go downhill fast in warm water. Monitor with an alarm if you can.
- Starvation: they hide, they skip meals, and faster fish eat everything. Check body condition weekly.
- Intake accidents: they can stick to surfaces near intakes and get pinned or pulled in. Use guards and sponge prefilters.
- Aggression and food theft: even "peaceful" fish can keep them from feeding.
- Shipping/transition stress: they often arrive skinny. Quarantine helps, but keep it calm and offer live foods immediately.
Be gentle with nets. Clingfish can get tangled and scraped up. If you have to move one, I prefer coaxing it into a container underwater rather than trying to peel it off glass or rock.
If one starts hanging out in the open more than usual, breathing harder, or moving perch to perch like it cannot settle, I take that as a stress signal. Check temp first, then check for harassment, then check if it is actually getting food into its mouth.
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