Banggai Cardinalfish

1) Where they come from

Banggai cardinalfish are from the Banggai Islands in Indonesia. They hang around calm, shallow areas—think seagrass beds, rubble, and urchin fields—where they can hover in place and duck into cover. That “hover and hide” vibe pretty much explains how they like to live in our tanks too.

2) Setting up their tank

These are one of the easier saltwater fish to keep, mostly because they’re not picky about fancy flow or needing a giant tank. Give them a stable, peaceful setup and they settle in fast.

Tank size-wise, a single Banggai can live in a 20 gallon, but I like 30+ because it gives you more room to aquascape and keeps parameters steadier. If you want a pair, bigger is nicer—especially if you’re still learning the saltwater rhythm.

• Rockwork with caves/overhangs: they love hovering near cover
• Moderate flow (they don’t need a washing machine)
• Normal reef lighting is fine; they don’t care much either way
• Stable salinity and temp matter more than chasing “perfect” numbers

3) What to feed them

Banggais are basically little ambush predators. In the wild they pick off small crustaceans, and in the tank they usually take to frozen pretty quickly—especially captive-bred.

• Frozen mysis (my go-to staple)
• Enriched brine shrimp (great for getting a shy new fish eating, but don’t make it the only food)
• Finely chopped krill or clam for variety (small pieces)
• Small pellets once they recognize them (soak first if they spit them)

I’ve had the best luck feeding smaller amounts more often at first—2 times a day—then backing off once they’re settled. Watch their belly line: a Banggai that’s eating well looks a bit rounded, not pinched.

4) Behavior and tankmates

They’re peaceful, slow-moving fish. Most of the time they just hover, face into the current a bit, and watch the world go by. That calm nature is great… until you pair them with fast, pushy eaters.

The big gotcha: Banggais can be mean to other Banggais. A group of juveniles looks cute for a while, then they hit maturity and you can end up with one dominant fish that bullies the rest.

• Good tankmates: clownfish (not super aggressive ones), gobies, blennies, small wrasses that aren’t jerks, reef-safe peaceful fish
• Use caution: dottybacks, aggressive damsels, bigger hawkfish, anything that outcompetes them hard at feeding time
• Avoid: predators that see “small slow fish” as a snack (bigger groupers, lionfish, etc.)

5) Breeding tips

Breeding Banggais is one of the coolest things you can do as a beginner because they’re mouthbrooders. The male carries the eggs (and later the babies) in his mouth for a few weeks. You’ll notice he stops eating and his jaw looks “full.”

• Keep a bonded pair in a calm tank (less stress = better odds)
• Feed the pair heavy before a spawn—mysis and other meaty foods
• Once the male is holding, keep things peaceful and don’t rearrange the tank
• Be ready with a small nursery/box or a separate tank if you want to raise fry

When he releases, the babies are surprisingly big and can take baby brine shrimp and sometimes even finely chopped frozen foods pretty quickly. The trick is keeping the fry from getting sucked into overflows or picked off by tankmates.

6) Common problems to watch for

Most issues with Banggais come down to stress, getting outcompeted for food, or bringing home a fish that wasn’t in great shape to begin with.

• Refusing food / weight loss: often from bullying, too much competition at feeding time, or a shy fish in a busy tank
• Ich/velvet: they can get the usual saltwater parasites, especially after shipping stress
• Damaged fins: usually from aggression (often another Banggai, or a nippy tankmate)
• Sudden hiding and breathing hard: check ammonia, oxygen, temperature swings, and any recent chemical/aerosol exposure