Flame cardinalfish
Fowleria amblyuroptera
The Flame cardinalfish exhibits a striking red body with distinctive black spots and elongated fins, contributing to its vibrant appearance.
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About the Flame cardinalfish
Fowleria amblyuroptera is a very small Indo-Pacific/Western Pacific cardinalfish (to about 4 cm SL) associated with coastal reefs/bays and is primarily nocturnal. Like many cardinalfishes, the male mouthbroods the eggs; in captivity it should be provided with ample shelter and offered appropriately sized meaty foods/planktonic items.
Quick Facts
Size
4 cm SL
Temperament
Peaceful
Difficulty
Intermediate
Min Tank Size
20 gallons
Lifespan
3-6 years
Origin
Indo-West Pacific
Diet
Carnivore - small meaty foods like mysis, brine shrimp, copepods, finely chopped seafood, and small pellets
Water Parameters
24-28°C
8.1-8.4
8-12 dGH
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This species needs 24-28°C in a 20 gallon tank. Use our heater calculator to find the right wattage.
Calculate heater sizeCare Notes
- Give them lots of rockwork and caves - they like to hover and retreat fast when spooked, and they color up way better when they have cover.
- Maintain stable marine conditions (reef-appropriate salinity/specific gravity and temperature) and avoid rapid parameter swings; provide shelter for this small, mostly nocturnal cardinalfish.
- They are small-mouthed pickers, so feed small stuff: mysis shaved small, brine with enrichment, copepods, and fine pellets - 1-2 small feedings beats one big dump.
- They can be shy at feeding time in a busy tank, so use a turkey baster to target feed near their hideout until they learn the routine.
- Tankmates: peaceful reef fish are best (gobies, blennies, small wrasses); skip pushy eaters and bullies like big dottybacks, hawkfish, and aggressive clownfish that will keep them pinned in the rocks.
- They are usually fine in groups if the tank has enough caves, but watch for one fish getting excluded from food - that is when you start seeing the skinny, pinched-belly look.
- Breeding is cool if you luck into a pair: the male mouthbroods, so if you see one holding and not eating, keep stress low and keep food available for the female; the male will spit out fully formed babies.
- Common issues are starvation (they can quietly fade away) and getting outcompeted, plus the usual marine stuff like flukes/ich - quarantine helps because once they stop eating, they go downhill fast.
Compatibility
Good Tankmates
- Other small, peaceful reef fish like firefish (Nemateleotris) - they mostly just hover and mind their own business, so the flame cardinal can do its shy, hang-in-the-water-column thing without getting bullied
- Clownfish that are on the calmer side (ocellaris or percula) - especially if the clowns have their spot and do not roam the whole tank picking on newcomers
- Small gobies and blennies (watchman goby, tailspot blenny) - different turf, different habits, and they are not usually interested in harassing a hovering cardinal
- Chill wrasses like a flasher wrasse or fairy wrasse (the more mellow ones) - active but usually not out to bully cardinals, and they do not compete hard for the same hidey spots
- Reef-safe darting fish like chromis (in reasonable groups and not overcrowded) - they add movement without being up in the cardinal's face all day
- Small, peaceful tangs in bigger tanks (like a tomini bristletooth) - they are busy with algae and cruising, and generally ignore cardinals if there is enough room
Avoid
- Aggressive or highly territorial fish that may harass or outcompete this small, shy cardinalfish (e.g., many dottybacks).
- Hawkfish - they are perch-and-pounce types, and even if they do not eat the cardinal, they can harass it and keep it pinned in the rocks
- Aggressive damselfish (three-stripe, domino, etc.) - constant attitude, constant chasing, and the cardinal is too peaceful to deal with that long term
- Big predatory stuff like groupers, lionfish, and large dottybacks - if it fits in their mouth, it is on the menu, and flame cardinals are bite-sized
Where they come from
Flame cardinalfish (Fowleria amblyuroptera) come from Indo-Pacific reefs, where they hang around shady ledges and rubble zones. You will usually see them hovering in small groups in the dimmer parts of the reef, picking at tiny drifting food.
That background pretty much explains how they act in an aquarium: they like cover, they like calm, and they are way more confident once the lights are not blasting and they have a place to tuck into.
Setting up their tank
Think "quiet corners and shade." They do not need a huge tank for swimming laps, but they do need structure. I have had the best luck when there are a few caves and overhangs they can claim, plus a bit of open water in front to hover and feed.
- Tank size: I would not do less than 20-30 gallons for one, and 40+ if you want a small group
- Rockwork: overhangs, arches, and tight crevices (they love a shadow line)
- Flow: moderate is fine, but give them a low-flow pocket so they can hover without fighting the current
- Lighting: they are happier with plenty of shaded areas; you do not need a dim tank, just break up the light
- Cover: a lid helps - they are not famous jumpers like some fish, but startled cardinals can still launch
If your flame cardinal hides for the first week, do not panic. Feed small amounts right near its cave and it will usually start showing itself once it learns the tank is safe and food appears regularly.
What to feed them
These are planktivore-style feeders. Mine did best on small meaty foods offered more than once a day. They can be picky right after shipping, so having a couple options ready makes life easier.
- Frozen: mysis (smaller pieces), finely chopped krill, calanus, brine shrimp (better as a starter than a staple)
- Live (great for new or shy fish): enriched baby brine, copepods
- Prepared: small sinking pellets or soft micro pellets once they recognize food
Target feeding works really well. Use a turkey baster or pipette and gently puff food into the water column right in front of their hiding spot. They are hover-and-sip feeders more than "charge the surface" fish.
Watch their belly line. A well-fed flame cardinal looks a little rounded behind the head. If they stay pinched, they are either getting outcompeted or you are feeding stuff that is too big for them to bother with.
How they behave and who they get along with
They are peaceful, a bit shy, and kind of "hovering furniture" once they settle in. They do not usually pick fights, but they also do not win them. The biggest issue is getting them bullied off food.
- Good tankmates: gobies, blennies, firefish, small wrasses that are not pests, peaceful tangs in bigger tanks
- Use caution: dottybacks, aggressive clownfish, big damsels, hawkfish (some will stalk them), overly pushy wrasses
- Predators to avoid: anything that can fit them in its mouth, especially groupers, big lionfish, and large anglers
Do not assume "it is a cardinalfish so it will be fine in a group." Some individuals tolerate others, some do not. If you want multiples, add them at the same time and give them several separate hiding spots so one fish cannot guard the whole area.
In a community reef, their main job is to look cool and eat small foods. If you keep fast eaters like anthias or aggressive clowns, plan to feed in two spots so the flame cardinal actually gets its share.
Breeding tips
Like many cardinalfish, this species is a mouthbrooder (the male carries the eggs). In a calm tank with a bonded pair, you might see the male stop eating and hold a clutch. He will look like he is "chewing" and his mouth will stay slightly puffed.
- Keep the tank low-stress: stable salinity and temperature, no constant chasing from tankmates
- Feed the pair well before spawning: lots of small meaty foods
- If the male is holding, do not keep trying to make him eat - it usually just makes him spit the clutch
- Expect tiny fry: you will need appropriately sized live foods (rotifers/copepods) if you want to raise them
If you are not set up for fry, do not sweat it. Most hobbyists just enjoy the behavior. Raising mouthbrooding cardinalfish fry is doable, but it is a separate project with live food cultures and a dedicated rearing setup.
Common problems to watch for
Most issues I have seen with flame cardinals come down to stress, shipping, and not eating enough. They are tough once settled, but the first couple weeks are where you win or lose them.
- Refusing food: try smaller foods (calanus, chopped mysis), offer live baby brine to kickstart feeding, and target feed near their cover
- Getting outcompeted: feed a second spot, use a feeding tube/baster, or rearrange rock so they have a protected "dining area"
- External parasites (marine ich/velvet): watch for flashing, heavy breathing, and dusting; quarantine is your friend with cardinals
- Bacterial issues after shipping: frayed fins, cloudy eyes, redness - usually tied to stress and poor acclimation
- Slow fade from bullying: they may hide constantly and lose weight even if the tank looks peaceful at a glance
Heavy breathing and hanging in the flow with a "dusty" look can go bad fast (velvet is the usual fear). If you see that, do not wait it out. Move the fish to a treatment setup and act quickly.
My general rule with these: if they are eating and coming out at feeding time, you are doing fine. If they are always pinned in a corner and staying skinny, change something early rather than hoping they will magically settle.
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