Apollo Shark (Luciosoma setigerum)

Choose an Apollo Shark only for a very large aquarium

The Apollo Shark (Luciosoma setigerum) is a long, slim, silver fish from the rivers of Southeast Asia, with a dark stripe along its side and long thread-like extensions on its pelvic fins. Despite the trade name, it is not a shark. It belongs to the carp and minnow group: FishBase places it in the family Danionidae, subfamily Chedrinae, while the Seriously Fish species profile still lists it under Cyprinidae.

Its genus name joins the Latin lucius, probably the pike, with the Greek sôma, body, a fair description of its long, pike-like shape. The species name setigerum means "bristly" and presumably refers to the first pelvic-fin ray, which is drawn out into a long filament. Older names you may find attached to it include Barbus setigerus, Barbus podonemus and Luciosoma weberii, and shops also call it the Apollo shark minnow.

Decide from the complete care picture

Seriously Fish rates it difficult for one reason above all: it needs a tank at least 2 m long. This is a fish for keepers who already own, or are ready to buy, a very large aquarium, and who want a fast, sleek surface swimmer as the main feature of it.

Confirm what you are buying

One purchase supplies one live Apollo Shark. It is sold in one standard size with no size grade; whatever its size on arrival, plan the aquarium for the adult size given below. Sex is not selected, and Seriously Fish notes only that mature females are likely to be deeper-bodied than males. Choose the quantity in the basket to buy a group in one delivery, and check our delivery page for dispatch days and arrival terms.

The photographs show the species, not the individual you will receive. That matters more than usual with Luciosoma: Seriously Fish reports that young L. setigerum, L. bleekeri and an unidentified L. cf. setigerum all reach the trade regularly, often under the wrong scientific name. The name L. spilopleura is widely used for traded fish although that species may never have been collected for aquariums, and the name L. pellegrinii is regularly misapplied.

Check these identification marks

These features come from Seriously Fish and the FishBase species summary. Judge the markings once the fish has settled, under normal aquarium lighting.

Plan the aquarium around the adult size

Seriously Fish gives a maximum of 220 mm standard length, measured without the tail; FishBase records 26.0 cm standard length. Either way, the body alone of a grown fish can exceed 20 cm, and it spends its life cruising at speed.

Seriously Fish's minimum base is 240 × 60 cm, about 864 litres, and it describes that as the smallest that should be considered; it adds that Luciosoma species are only suitable for the largest private aquariums. Our tank volume calculator converts length, width and height into litres.

Use a three-step space check

1. Measure the base: at least 240 cm long and 60 cm from front to back.
2. Count complete groups: the whole Apollo group plus every other fish at its adult size.
3. Check the total: run the full stock list through our stocking calculator.

Buy and mature the final aquarium before you buy the fish. A fast swimmer that hunts at the surface needs length to turn and cruise, and moving a group of long, nervous fish into a bigger tank later adds stress for them and work for you. Our tank set-up guide explains how to mature a new aquarium before stocking it.

Build a river layout with open surface water

FishBase describes it living at the surface of flowing water, in river main channels and gently sloping tributaries with logs and leaf litter on the bottom. Seriously Fish describes slow-flowing lowland rivers with leaf litter and sunken wood, and notes that the fish moves into swamps and flooded forest in the wet season. Its range covers the Mekong basin (Thailand, Laos, Cambodia and Vietnam), the Chao Phraya and Mae Klong, peninsular Thailand and Malaysia, Borneo, Sumatra and Java; records from eastern Myanmar still need confirmation.

Seriously Fish says décor matters less than water quality and open swimming space, and suggests a stream-style tank with water-worn rocks, sand, fine gravel, perhaps a few small boulders, and driftwood roots or branches. Hardy plants such as Java fern (Microsorum), Bolbitis and Anubias can be tied to the décor; most other aquatic plants will not thrive.

Divide the footprint by function

Fit a tight cover before the fish arrives

Seriously Fish is blunt: every Luciosoma species is an accomplished jumper, and the tank must have a very tightly fitting cover. A fast fish that spends its time just below the surface has every chance to find a gap, so make the lid escape-proof before the fish is in the tank, not after the first jump.

Check the lid in five places

1. Cut-outs for filter pipes and heater cables: close them with foam or fine mesh.
2. The feeding hatch: it should close fully after every feed.
3. The rear strip, where many lids stop short of the back glass.
4. The joins between lid panels on a long tank.
5. Light units that sit in place of a lid section.

Keep the lid in place during maintenance as far as you can. We also suggest switching the room lights on before the tank lights, so the fish is not startled by sudden brightness.

Set water values and keep oxygen high

The upper hardness limit is the one to check in the UK. Tap water ranges from soft to very hard depending on the region, and in hard-water areas it can exceed 12 dGH. Test yours and, if needed, blend it with reverse-osmosis water to bring it into range. Our water matcher compares your water with each fish's needs, and our water chemistry guide explains hardness and pH.

Seriously Fish says very fast flow is unnecessary, but the water must hold a relatively high level of dissolved oxygen with moderate movement. Filter outlets that ripple the surface help with that.

Separate habitat values from waste readings

Temperature, pH and hardness describe the habitat and can sit anywhere inside the range. Ammonia, nitrite and nitrate measure waste and have fixed targets whatever the habitat values. In a tank of this size, with large fish eating meaty food, waste builds up quickly, so test weekly and act on any reading above target.

Filter and change water for a big, active group

Seriously Fish recommends weekly water changes of 30–50% for this species; OATA's general guidance for freshwater sharks is at least 25% every week. On a tank of 800 litres or more that means moving a lot of water, so plan the method, such as a long hose, a pump and a dechlorinator dosed for the full volume, before the fish arrives. Seriously Fish's equipment suggestion for a tank this size is three external filters rated 1,150–1,440 litres per hour each, with the heating split across three heaters. Our guide to aquarium filtration explains how to size a filter.

Follow a weekly maintenance sequence

1. Test ammonia, nitrite, nitrate, pH and hardness.
2. Siphon waste from the substrate and remove 30–50% of the water.
3. Refill with conditioned water close to tank temperature, keeping the lid closed over the fish as far as possible.
4. Rinse filter media only when flow drops, and only in removed tank water.
5. Check every lid gap again before you walk away.

Feed at the surface, as it does in the wild

The sources disagree on its natural diet. Seriously Fish says it feeds mainly on land insects taken at the water's surface, and presumably also on aquatic invertebrates and fish fry. FishBase, citing the FAO field guide to the fishes of the Cambodian Mekong, says it feeds mostly on fish. Either way, it is a surface-feeding predator, and small fish are at risk.

In the aquarium, offer foods that stay at or near the surface: floating pellets or sticks sized for its mouth, insect-based dried foods, and thawed frozen foods such as bloodworm, brine shrimp and krill. OATA's general rule is to feed once a day and give only what is eaten within a few minutes, because uneaten food fouls the water.

Build one measured meal

1. Choose the size: food small enough for the smallest fish in the group to swallow.
2. Spread it: scatter it along the length of the tank so the fastest fish cannot take it all.
3. Watch: make sure every Apollo Shark gets some within a few minutes.
4. Remove leftovers: net out anything that sinks uneaten.

Introduce the group to a mature aquarium

Add Apollo Sharks only to a fully mature tank: OATA says ammonia and nitrite must read zero before any fish go in. Introduce the whole group together where you can, so the fish settle as a group rather than one at a time.

OATA's floating-bag method works well: switch off the aquarium lights, float the sealed bag for about 10 minutes to equalise the temperature, then add small amounts of tank water to the bag over up to 20 minutes before netting the fish into the tank, keeping bag water out. With this fish, close the lid immediately after each one goes in. Our acclimatisation guide covers the same steps in more detail.

Use a first-week checkpoint plan

Choose tank mates that are big and calm enough

Seriously Fish says it needs to be kept in a group and is fine with other fish, but its diet means small companions can become food. Pick tank mates that are too large to swallow, robust enough not to be stressed by fast swimmers, and happy in the same 20–26°C range.

Use the same five questions every time

1. Do the water ranges overlap? Check every companion against 20–26°C, pH 6.0–8.0 and 2–12 dGH.
2. Is every fish too big to swallow? Compare mouth size with the smallest companion, at the size it is now.
3. Does each species get its full group? Count the complete groups, not single fish.
4. Is there still open water? The upper half of the tank belongs to the Apollo group.
5. Can every fish feed? Watch feeding for the first weeks after any new fish goes in.

Our tank mates tool checks a planned mix for you. For more large, active fish, browse our barbs and shark-type cyprinids, the Barbs category page, our schooling fish and our rare and collector fish.

Watch health and behaviour

OATA lists the signs of a healthy fish as clear, bright eyes, undamaged fins, intact scales, no ulcers or bumps, normal swimming and steady breathing. Signs of trouble include clamped fins, flicking against objects, white spots or fluffy growths, hiding more than usual, faster or slower gill movement and a reduced appetite. Because this fish lives at the surface, its position alone is not a warning sign; watch its breathing and feeding instead.

Pair each observation with an action

Answer Apollo Shark buying questions

Is the Apollo Shark a real shark?

No. It is a cyprinid (Danionidae in FishBase, Cyprinidae in Seriously Fish), related to danios and barbs. "Shark" is only a trade name.

How big does an Apollo Shark get?

Seriously Fish gives 220 mm standard length and FishBase 26.0 cm standard length, both measured without the tail.

What size aquarium does it need?

A base of at least 240 × 60 cm, about 864 litres, which Seriously Fish describes as the smallest that should be considered.

Can I keep just one?

Seriously Fish says it needs to be kept in a group, so plan for several fish in a tank large enough for all of them.

Will it eat my small fish?

It may. FishBase says it feeds mostly on fish, and Seriously Fish expects it to take fry. Keep it only with fish too big to swallow.

Does it jump?

Yes. Seriously Fish calls all Luciosoma accomplished jumpers and says the tank needs a very tightly fitting cover.

What water does it need?

20–26°C, pH 6.0–8.0 and 2–12 dGH, with moderate movement and plenty of dissolved oxygen, plus zero ammonia and nitrite.

How can I tell it from other Luciosoma?

Look for spots on the lateral-line scales, a stripe ending in a black blotch at the base of the upper tail lobe and a dark stripe inside the edge of the lower lobe. L. bleekeri lacks the lateral-line spots.

What size will I receive?

One live fish in our standard size. It is sold without a size grade and is not an adult, so plan for the full adult size.

Consult the care references

• Seriously Fish: Luciosoma setigerum: names and etymology, distribution, habitat, adult size, minimum base, water values, décor, cover, water changes, diet, identification and trade confusion.
• FishBase: Luciosoma setigerum: classification, maximum recorded length, identification features, habitat and diet (after Rainboth 1996).
• OATA: How to look after freshwater sharks: water quality targets, weekly water changes and the floating-bag acclimatisation method.