Rippled rockskipper

Where they come from

Rippled rockskippers (Istiblennius edentulus) are the kind of fish you notice because they act like they own the shoreline. In the wild they hang around shallow reef flats, rocky tide pools, and surge zones across the Indo-Pacific. Lots of sun, lots of algae, water levels that change, and waves that slap the rocks all day.

That background explains most of their personality in a tank: they want perches, they want to graze, and they really like having a little territory to supervise.

Setting up their tank

Think "shoreline with hiding holes" more than "open swimming space." Rockskippers are blennies, and they spend a ton of time parked on rock ledges, wedged into crevices, and hopping from spot to spot.

• Tank size: 20 gallons works for a single adult, but 30+ gallons is way easier if you want tankmates or more rockwork.
• Rockwork: build a bunch of small shelves and caves at different heights. They love a tight bolt-hole where only they fit.
• Flow: moderate, not a sandstorm. They like clean, oxygen-rich water, but they still need calm perches.
• Lighting: bright enough to grow film algae and encourage grazing. If your tank is sterile-clean, they get bored (and hungry).
• Lid: use one. They can and will hop, especially if spooked or chased. Tiny gaps around plumbing count.

What to feed them

These guys are mostly algae and micro-stuff grazers with a side of meaty snacks. The biggest mistake I see is treating them like a pure carnivore and only offering frozen mysis. They might eat it, but they do better long-term with regular plant-based food and grazing options.

• Daily staples: spirulina flakes, quality herbivore pellets, and sheets of nori on a clip.
• Frozen rotation: mysis, brine (better if enriched), chopped krill, and a little clam or shrimp now and then.
• Grazing: let some rocks get a light film algae coating, or keep a small "algae rock" in a lit sump/refugium and swap it in.
• Frequency: small amounts 1-2 times a day, plus nori most days. They like to pick all day rather than smash one huge meal.

How they behave and who they get along with

Personality-wise, they're classic blenny: curious, a little grumpy, and way braver than their size suggests. They will claim a patch of rock and defend it, especially against other blennies or fish with a similar shape.

With the right tankmates they are totally doable in a community reef, but you want to avoid roommates that either bully them off the rocks or compete for the same niche.

• Good tankmates: calmer gobies, small wrasses that stay in the water column, cardinalfish, chromis, and most peaceful reef fish.
• Use caution: other blennies, hawkfish (can be pushy on perches), and very bold dottybacks.
• Avoid: aggressive damsels in small tanks, large predators, and anything that will constantly harass a bottom-percher.

Breeding tips

They can spawn in captivity, but raising the babies is the hard part. Like many blennies, they lay eggs in a tight cavity and the male typically guards and fans them. If you ever notice a fish refusing to leave a hole and looking extra defensive, check for a patch of tiny eggs inside.

• Provide spawning sites: small caves, short sections of PVC tucked into rockwork, or narrow crevices they can claim.
• Conditioning: heavier feeding with a mix of algae-based foods and frozen helps get them in the mood.
• If you want to raise larvae: plan on a separate larval setup and appropriate tiny live foods. The larvae are planktonic and not "easy first fry."

Common problems to watch for

Most issues I have seen with rockskippers come down to diet, stress from tankmates, or jump-outs. They are hardy once settled, but they don't love being shoved around.

• Not eating or slowly losing weight: usually a tank that's too "clean" and a diet that's too meaty. Add more algae-based foods and offer nori consistently.
• Fin damage and scrapes: often from fighting over holes or squeezing into rough rockwork. Add more caves and smooth out the worst spots.
• Jumping: happens after a chase, sudden lights-on, or during acclimation. Use a tight lid and keep the tank calm the first week.
• Ich/velvet after purchase: stress-related like any marine fish. Quarantine if you can, and avoid big salinity/temperature swings.
• Getting bullied off perches: they need a calm territory. Rehome the bully or rearrange rockwork to reset territories.