Kermadec dwarfgoby

Where they come from

Kermadec dwarfgobies (Eviota kermadecensis) come from the Kermadec Islands area in the South Pacific. Think steep reef slopes, rubble, and little nooks where tiny fish can disappear in a blink. They are true micro-predators that live life close to the rockwork.

They are also one of those fish that looks "easy" because it is small. In practice, they are advanced because they need the right food, low stress, and a tank that is already stable.

Setting up their tank

If you want this fish to last, put it in an established reef. New tanks swing too much and these little gobies do not forgive you for it.

• Tank size: you can keep one in a small reef, but I have the best luck starting at 15-20 gallons simply because stability is easier.
• Mature rockwork: lots of holes, ledges, and tight crevices. They perch and hop, not cruise in open water.
• Flow: moderate, with calmer pockets behind rocks. They like to sit in the lee and dart out for food.
• Lighting: any reef lighting is fine, but give shaded spots so they can retreat.
• Cover: a lid or mesh top. Tiny gobies can and do carpet-surf if spooked.

For parameters, think normal reef numbers and keep them steady: 1.025-ish salinity, temp in the mid to upper 70s F, and low nutrients without chasing zeros. The big thing is avoiding sudden swings from big water changes, dosing mistakes, or a pH/alk roller coaster.

What to feed them

This is where most people lose Eviota gobies. They have tiny mouths and they are built to peck at small moving prey all day. If your tank only gets one big feeding, they may not get enough even if they look like they are trying.

• Best staples: live baby brine shrimp (newly hatched), live copepods, live adult brine enriched, small live mysids if you can get them.
• Frozen options (often accepted once settled): cyclops, calanus (the smaller bits), finely shaved mysis, roe/masago style micro eggs.
• Prepared foods: some individuals learn pellets, but I would never buy one assuming it will. Treat that as a bonus, not a plan.

I like to start them with live foods for the first week or two, even in a tank with pods. Once they are confidently eating, you can mix in frozen. Feed small amounts 2-4 times a day if you can. If you only feed once, make that one feeding count with something small and dense like cyclops.

How they behave and who they get along with

Kermadec dwarfgobies are classic perch-and-dart fish. They pick a little territory, watch everything, and snap at passing micro food. They are not aggressive in the usual sense, but they are bold for their size once settled.

• Good tankmates: other peaceful nano fish, small blennies, small dartfish, tiny assessors, calm wrasses that do not hunt pods aggressively.
• Use caution: very active fish that hog food (anthias, chromis groups), pod-hunting wrasses, and anything that constantly patrols the rockwork.
• Avoid: hawkfish, bigger dottybacks, most large wrasses, lionfish, scorpionfish, and basically anything that thinks "tiny fish" is a food group.

With other Eviota, it depends on tank size and rockwork. In cramped quarters, two can stress each other out. In a bigger, complex scape with multiple perch zones, you can sometimes keep a pair or a small group, but you need to watch for one getting pushed off food.

Breeding tips

They are egg layers, and like many dwarfgobies they will use a tight little cavity as a nest. In a calm, well-fed tank, you might see a pair hanging around a specific hole and the male guarding it more than usual.

Raising the babies is the hard part. The larvae are tiny and need live plankton (think rotifers first, then copepod nauplii). If you have never raised marine larvae, consider it a fun side project rather than something that will just happen in the display.

• Give them nest options: small caves, empty snail shells, or tight gaps under rubble plates.
• Condition with food: frequent small feedings of live/frozen micro foods seems to trigger breeding behavior.
• If you want to raise fry: you will likely need a separate larval setup and a steady live food culture.

Common problems to watch for

Most losses with this fish look like a mystery because they do not show dramatic symptoms. They just get thinner, perch more, and one day they are gone. Usually it comes down to food intake, stress, or both.

• Slow starvation: belly looks pinched, head looks a bit "pointy," fish stops darting for food.
• Getting outcompeted: you feed, everyone else eats, the goby pecks a few times and gives up.
• Shipping damage and refusal to eat: common with tiny species. Some never settle if the first few days go poorly.
• Jumping: especially right after introduction or during a tankmate dispute.
• Parasites: marine ich and velvet can hit them like anything else, but they can crash faster due to their small body mass.

My best practical advice: quarantine if you can, but do it in a way that lets them eat. A bare box with PVC and harsh light can make them shut down. Dim the tank, add a little rock-like shelter (even inert), and be ready with live foods. The first week is where you win or lose them.