What Flying Fox Are and Where They Live

Flying fox is the common name for several species of freshwater fish in the family Cyprinidae, most commonly the red-tailed black shark (Epalzeorhynchos bicolor) and the Chinese algae eater (Gyrinocheilus aymonieri). Despite their name, they do not fly — the name comes from their dark coloring and the way they dart through water with quick, darting movements. In the wild, flying fox inhabit slow-moving rivers, streams, and floodplain areas across Southeast Asia, particularly Thailand, Laos, and Cambodia.

Flying fox are bottom-dwellers that spend most of their time near rocks, logs, and vegetation where they feed on algae, small invertebrates, and plant matter. They prefer warm water between 72 and 82 degrees Fahrenheit and are most active in low-light conditions — early morning and dusk. In their native habitat, they occupy areas with moderate current and plenty of hiding places, though they adapt well to still water as long as there is adequate cover and food.

Key Takeaways

  • Flying fox are bottom-feeding fish native to Southeast Asia that eat algae and small invertebrates, making them popular for aquarium maintenance rather than sport fishing.
  • They are rarely targeted by recreational anglers because they are small (most under 6 inches), difficult to catch on hook and line, and not found in North American waters outside of aquariums.
  • In their native range, flying fox inhabit warm, slow-moving rivers and streams with plenty of vegetation and hiding cover.
  • If you encounter flying fox in an aquarium setting, they require warm water, live plants, and a diet of sinking pellets and algae wafers to thrive.

Why Flying Fox Are Not a Fishing Target

Flying fox do not appear on any recreational fishing lists in North America because they are not native to any public waters here. They are exclusively an aquarium fish in the United States and Canada, imported from Southeast Asia for the ornamental trade. Even in their native countries, they are too small and too difficult to catch on conventional tackle to interest sport anglers — most individuals weigh less than 2 ounces and rarely exceed 5 or 6 inches in length.

Their feeding behavior also makes them unsuitable for hook-and-line fishing. Flying fox are bottom-feeders that graze on algae and small organisms rather than hunting larger prey. They do not respond to standard fishing baits or lures, and their small mouths cannot accommodate typical freshwater hooks. If you are looking for a freshwater fish to catch, flying fox should not be on your list — they belong in an aquarium, not on the end of a line.

Identifying Flying Fox in an Aquarium

The red-tailed black shark is the most recognizable flying fox species. It has a jet-black body with a bright red or orange tail fin, making it unmistakable in an aquarium. The body is elongated and slightly flattened, with a small, downward-facing mouth adapted for feeding on surfaces. Adults typically reach 4 to 6 inches, though some individuals in well-maintained aquariums may grow slightly larger.

The Chinese algae eater is less colorful but equally distinctive. It has a mottled gray or brown body with a sucker-like mouth on its underside — a feature that distinguishes it from other algae-eating fish. Young Chinese algae eaters are often pale yellow or tan, darkening as they mature. Both species have a flattened belly and a streamlined body shape that allows them to move quickly along the substrate and hide in tight spaces.

Aquarium Care and Feeding

If you keep flying fox in an aquarium, they require warm water maintained between 72 and 82 degrees Fahrenheit, which means a heater is essential in most home setups. They prefer slightly acidic to neutral water with a pH between 6.0 and 7.5 and moderate water movement — not a strong current, but enough circulation to prevent stagnation. A 40-gallon tank is the minimum for a single flying fox, and larger tanks are better because these fish are territorial and need space to establish separate feeding areas.

Flying fox eat primarily algae and plant matter, but they also consume small invertebrates and prepared foods. In an aquarium, feed them sinking pellets designed for bottom-feeders, algae wafers, and blanched vegetables like zucchini or spinach. They will graze on algae naturally present in the tank, but most aquariums do not produce enough algae to sustain them alone. Provide hiding places with rocks, driftwood, and dense plants — flying fox are shy and stressed by open, exposed tanks. They are most active at dawn and dusk, so do not be alarmed if they hide during the day.

Behavior and Tank Compatibility

Flying fox are territorial fish, especially as they mature. A single flying fox may coexist peacefully with other species, but two flying fox in the same tank often fight, particularly if they are similar in size or if the tank is too small. Aggression typically escalates over time, so monitoring is essential. They are generally safe with larger fish that do not view them as food, but they may harass smaller fish or fry.

Red-tailed black sharks are more aggressive than Chinese algae eaters and are more likely to chase or nip at other fish. Chinese algae eaters become increasingly territorial and aggressive as they age, sometimes attacking other bottom-feeders or even fish that occupy the middle water column. Both species are nocturnal and most active when the aquarium lights are off, so you may see little of them during the day. This behavior is normal and does not indicate illness or stress.

Common Misconceptions About Flying Fox

A widespread myth is that flying fox will control algae indefinitely in an aquarium. In reality, they eat algae when it is abundant, but they cannot sustain themselves on algae alone in most tanks, and they do not prevent algae blooms. As they mature, they often stop eating algae altogether and rely on prepared foods instead. Expecting a flying fox to solve an algae problem without other interventions — such as reducing light hours or controlling nutrient levels — will disappoint you.

Another misconception is that flying fox are suitable for small tanks or community aquariums with many species. They are not. Their territorial nature, specific temperature requirements, and need for hiding places make them poor choices for beginners or for tanks smaller than 40 gallons. They are also sometimes confused with plecos or other algae-eating fish, but they have different care requirements and behaviors. If you are new to fishkeeping, research flying fox thoroughly before purchasing one.

Where to Find Information About Flying Fox Care

If you own or plan to own a flying fox, consult species-specific care guides from established aquarium organizations or experienced aquarists. The Aquarium Co-op and FishLore both maintain detailed care sheets for red-tailed black sharks and Chinese algae eaters, including water parameters, tank size recommendations, and feeding schedules. Local aquarium clubs often have members with hands-on experience keeping flying fox and can answer questions about behavior and compatibility.

Your local aquarium store staff may also provide guidance, though quality varies. Ask whether the store has kept flying fox themselves and what their experience has been with aggression and long-term care. Avoid purchasing flying fox on impulse or based solely on their appearance — they are not beginner fish, and they require commitment to proper care and monitoring.

Frequently Asked Questions

Can I catch flying fox in the wild in North America?

No. Flying fox are native only to Southeast Asia and do not occur in any wild waters in North America. They are found only in aquariums and ornamental fish collections in the United States and Canada. If you want to fish for freshwater species, choose native fish like bass, trout, or panfish instead.

How long do flying fox live in an aquarium?

Red-tailed black sharks typically live 5 to 8 years in well-maintained aquariums, while Chinese algae eaters may live 10 to 15 years or longer. Lifespan depends on water quality, temperature stability, diet, and tank size. Overcrowding or poor conditions will shorten their lives significantly.

Why is my flying fox hiding all the time?

Flying fox are naturally shy and nocturnal, so hiding during the day is normal behavior. However, excessive hiding can also signal stress from poor water conditions, incompatible tank mates, or insufficient food. Check your water temperature, pH, and ammonia levels, and ensure the tank is not overcrowded or too brightly lit.

Can flying fox live together in the same tank?

Two flying fox of the same species rarely coexist peacefully, especially as they mature. They are territorial and will fight over space and food. A single flying fox per tank is the safest approach unless you have a very large aquarium (75+ gallons) with multiple hiding areas and feeding zones.

What should I feed my flying fox if there is no algae in the tank?

Feed sinking pellets formulated for bottom-feeders, algae wafers, and blanched vegetables like zucchini, spinach, or cucumber. Offer these foods three to four times per week, removing uneaten portions after a few hours to prevent water quality problems. Supplement occasionally with frozen bloodworms or small live foods if your flying fox will accept them.