Directory of Freshwater Fish
Cyprinids
The cyprinid family is the largest single grouping of freshwater fish. It includes not only popular tropical aquarium fish but also their coldwater counterparts, notably goldfish (Carassius auratus) and koi (Cyprinus carpio). The majority of those kept in tropical aquariums have a strong shoaling instinct and are best kept in groups. Since a number of the most widely kept species are bred commercially on a large scale, color and fin variants occur, some of which have been developed into distinct ornamental strains.
Tri-Color Shark (Balantiocheilos melanopterus)
- ORIGINS: Southeast Asia, occurring in Thailand, the Malay Peninsula, Sumatra, and Borneo.
- SIZE: 12 in (30 cm).
- DIET: Live foods and flake.
- WATER: Temperature 72–77°F (22–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
- TEMPERAMENT: Relatively peaceful.
A silvery body and a deeply forked yellowish caudal fin edged with black help to identify Tri-Color Sharks. These active fish are fast swimmers and good jumpers, so they need to be caught with care. As they grow, the females can be recognized by the rounder shape of their underparts. Breeding requires more space than is available in the typical home aquarium. Large Tri-Color Sharks may prey on smaller companions.
Siamese Flying Fox (Crossocheilus oblongus)
- ORIGINS: Southeast Asia, occurring in Thailand and the Malay Peninsula.
- SIZE: 51⁄2 in (14 cm).
- DIET: Algae and live foods.
- WATER: Temperature 72–77°F (22–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
- TEMPERAMENT: Relatively peaceful.
The Siamese Flying Fox has a broad, dark line along its body. It can be distinguished from the Flying Fox (see right) by its clear fins and the fact that it has just one set of barbels. There is no obvious way of sexing individuals. These fish are highly valued because they keep algal growth under control but do not damage aquarium plants. They need well-oxygenated water and often rest close to the bottom.
Flying Fox (Epalzeorhynchos kalopterus)
- ORIGINS: From northern India and Thailand to parts of Indonesia, including Sumatra and Borneo.
- SIZE: 6 in (15 cm).
- DIET: Algae and live foods.
- WATER: Temperature 72–77°F (22–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
- TEMPERAMENT: Relatively peaceful.
The Flying Fox has a body pattern very similar to its Siamese relative. It, too, feeds on algae, nibbling algal growth from rocks with its low-slung mouth. Flying Foxes require a range of other foods to supplement the algae in their diet, with worms being especially favored. The sleek body shape reflects the fact that these fish are strong swimmers that naturally inhabit fast-flowing water. They often become more territorial with age.
Red-Tailed Shark (Epalzeorhynchos bicolor)
- ORIGINS: Southeast Asia, occurring in Thailand, notably in the central area of the country.
- SIZE: 6 in (15 cm).
- DIET: Flake and small live foods.
- WATER: Temperature 72–79°F (22–26°C); soft to hard (50–150 mg/l) and acidic to neutral (pH 6.0–7.0).
- TEMPERAMENT: Intolerant of its own kind.
The velvet-black body of these cyprinids is offset by the bright red coloration of the tail. Females are larger than males, and their caudal fin is not as brightly colored. Breeding in the typical home aquarium is unrealistic because of their aggressive nature. A single fish in a community is unlikely to be disruptive, but avoid tankmates with a similar coloration, since they may be attacked. Young Red-Tailed Sharks are silvery at first, gaining their red caudal fin when about seven weeks old.
Red-Fin Shark (Epalzeorhynchos frenatus)
- ORIGINS: Southeast Asia, being restricted to northern parts of Thailand.
- SIZE: 6 in (15 cm).
- DIET: Flake and small live foods.
- WATER: Temperature 72–77°F (22–25°C); soft to hard (50–150 mg/l) and acidic to neutral (pH 6.0–7.0).
- TEMPERAMENT: Relatively peaceful.
One of the more colorful cyprinids, this fish can be distinguished at a glance from its red-tailed relative (see left) because all its fins are reddish in color. Red-Fin Sharks require an aquarium incorporating suitable retreats, such as a clay flowerpot set in the substrate, and some floating plants at the surface to create dappled lighting. These fish are more tolerant of their own kind than Red- Tails, so they can be bred more easily. The females swell with eggs, laying up to 4,000 at a single spawning. The resulting young are soon large enough to feed on brine shrimp.
The white form of the Red-Fin Shark is now widely available. It retains the reddish fin markings, but the body is mostly whitish or transparent.
ON THE ALERT
Fish rely on a range of senses to locate food, including smell, sight, and touch. There are significant differences in the sensory equipment and capabilities of different groups, and even of individual species within groups. Most cyprinids, such as the Red-Fin Shark pictured here, have paired sensory barbels. These help the fish find edible items in the substrate, keeping the eyes free to detect approaching predators. The barbels may not be conspicuous in some cyprinids because they keep them folded back along the side of the face, giving the fish a more streamlined shape when swimming.
Golden Bony-Lipped Barb (Osteochilus vittatus)
- ORIGINS: Southeast Asia, from Thailand across the Malay Peninsula to parts of Indonesia and Borneo.
- SIZE: 121⁄2 in (32 cm).
- DIET: Flake and small live foods.
- WATER: Temperature 72–77°F (22–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
- TEMPERAMENT: Peaceful.
Golden markings are apparent on the bodies of these barbs, which grow to a large size and need spacious accommodation. There is no visual difference between the sexes. Golden Bony-Lipped Barbs thrive in groups. They use their strong lips to dig around in the substrate in search of food and will uproot plants that are not set in pots. Should they start to nibble the plants, you may be able to deter them by offering foods such as spinach.
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