[Ebook] Encyclopedia of Aquarium & Pond Fish - Directory of Freshwater Fish - Cyprinids - Rasboras

Directory of Freshwater Fish

Cyprinids

Rasboras

Spotted Rasbora (Boraras maculatus)

ORIGINS: Southeast Asia, extending from western Malaysia southward to western Sumatra.
SIZE: 1 in (2.5 cm).
DIET: Flake and live foods.
WATER: Temperature 75–79°F (24–26°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

This rasbora is the smallest member not only of its group but also of the entire cyprinid family. The Spotted Rasbora has a long, narrow caudal peduncle with three dark spots along the side of the body. The pattern of dark markings differs between individuals. The males are recognizable by their brighter coloration and flat underparts; females have a slightly curved lower outline. Spotted Rasboras, which look best in shoals, can be mixed with suitable companions of a similar size, including other small rasboras. A pair will spawn in a breeding tank that is well planted with Sagittaria and cryptocorynes, but they will eat their eggs if left there. About 50 eggs are produced, and they hatch in about 36 hours. Very fine fry food is essential for the young fish at first.

Axelrod’s Rasbora (Sundadamo axelrodi)

ORIGINS: Southeast Asia, where this species is restricted to the Indonesian island of Sumatra.
SIZE: 1 1⁄4 in (3 cm).
DIET: Flake and live foods.
WATER: Temperature 73–79°F (23–26°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

These beautiful fish are instantly recognizable, since their body is fluorescent green on top and reddish below, with red coloration also evident on the ventral fin. Axelrod’s Rasboras appear to lack the sensory lateral line along the sides of the body, which is perhaps compensated for by their large eyes. Discovered in 1976, this species was named after Dr. Herbert Axelrod, a leading American ichthyologist and fishkeeper.

Glass Rasbora (Boraras urophthalmoides)

ORIGINS: Southeast Asia, where its distribution extends from Vietnam south to Sumatra.
SIZE: 1 1⁄2 in (3.5 cm).
DIET: Flake and live foods.
WATER: Temperature 73–77°F (23–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

These small, attractive rasboras have a red stripe running along each side of the body. There is a broader, iridescent area beneath this stripe that gradually tapers to a point along the caudal peduncle. Male Glass Rasboras have a very evident white spot at the base of the dorsal fin and a larger adjacent black area, both of which the females lack. Relatively dark surroundings, with bogwood decor and suitable plants, should help to overcome the natural nervousness of these fish. It has proved possible to breed Glass Rasboras in a planted spawning tank, provided that the water temperature is kept slightly higher than that in the main aquarium, at up to 82°F (28°C). About 50 eggs are laid on the underside of the leaves of cryptocoryne plants, after which the adult pair should be removed to protect the eggs. They hatch after about two days.

Orange-Finned Rasbora (Rasboroides vaterifloris)

ORIGINS: Southern Asia, restricted to the island of Sri Lanka.
SIZE: 1 1⁄2 in (4 cm).
DIET: Live foods, plus flake.
WATER: Temperature 77–84°F (25–29°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful.

The appearance of the Orange-Finned Rasbora differs across its range: individuals found between Valallavites and Meegahatenne are predominantly red, while specimens from around Gilimale on the Kaluganga River are greenish. The depth of the orange coloration around the eye socket also varies. Males are more colorful and slimmer-bodied than females. In addition to their regular diet, Orange- Finned Rasboras will sometimes take small amounts of pollen, available in health-food stores. Rich in protein, pollen can help to encourage spawning, as can live foods. Orange-Finned Rasboras are often the only fish that occur in parts of their natural habitat, but they can still be mixed with other nonaggressive fish in community aquariums. Their isolation in the wild may also explain why they have a shorter lateral line than other rasboras: being less exposed to predators, they may not have such a great need for this sensory warning system.

Big-Spot Rasbora (Rasbora kalochroma)

ORIGINS: Southeast Asia, where it is found in parts of Malaysia, Sumatra, and Borneo.
SIZE: 4 in (10 cm).
DIET: Flake and live foods.
WATER: Temperature 77–82°F (25–28°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

In spite of its relatively large size, the Big-Spot Rasbora is rather sensitive to water quality, and its true beauty will be apparent only if conditions are optimal. A dark base in the aquarium and subdued lighting are also needed for this fish to look its best. Big-Spot Rasboras should be kept in groups, but their shoaling instincts are not as strong as in other rasboras. Spawning behavior in home aquariums has not been documented, but it is probably similar to that shown by other rasboras.

Long-Band Rasbora (Rasbora einthovenii)

ORIGINS: Southeast Asia, occurring in Malaysia, Sumatra, and Borneo.
SIZE: 4 in (10 cm).
DIET: Flake and live foods.
WATER: Temperature 72–77°F (22–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

The dark stripe along the midline of this rasbora extends from the mouth all the way through to the caudal fin. It is broader in males, which have a purplish cast to the body and a hint of red on the dorsal fin; this coloration is most obvious when they are in top condition. Females, in contrast, are a more greenish shade. A spawning tank for these fish needs a concentration of fine-leaved plants at one end in which eggs can be laid.

Scissortail Rasbora (Rasbora trilineata)

ORIGINS: Southeast Asia, occurring in parts of Malaysia, Sumatra, and Borneo.
SIZE: 6 in (15 cm).
DIET: Flake and live foods.
WATER: Temperature 73–77°F (23–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

The striped pattern on the sides of the Scissortail Rasbora’s silvery body becomes more evident toward the caudal fin. This rasbora’s common name derives from the way the deep fork of the caudal fin tends to close up, like scissor blades, as the fish moves through the water. The size and shoaling behavior of Scissortail Rasboras means that they will benefit from being housed in a relatively long aquarium, where planting is restricted to the sides of the tank.

False Magnificent Rasbora (Rasbora borapetensis)

ORIGINS: Southeast Asia, found in parts of Thailand and western Malaysia.
SIZE: 2 in (5 cm).
DIET: Flake and live foods.
WATER: Temperature 72–79°F (22–26°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

False Magnificent Rasboras have a dark red area at the base of the caudal fin. They also display a black line that runs from behind the gills along the midline of the body. If their surroundings are less than ideal, the red area on the tail becomes much paler. Floating plants on the surface will ensure that the lighting is not too bright, while adding aquarium peat to the filtration system will help to maintain the water quality.

Elegant Rasbora (Rasbora elegans)

ORIGINS: Southeast Asia, on the Malay Peninsula, and southward to Sumatra and Borneo.
SIZE: 8 in (20 cm).
DIET: Flake and live foods.
WATER: Temperature 72–77°F (22–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

Elegant Rasboras display three black areas on each side of the body. The body itself is greenish- brown above and silvery below. Females can be recognized when spawning approaches, because they become paler than the males and their bodies swell with eggs. They spawn in typical rasbora fashion, with the young requiring special fry food or infusoria once they are free-swimming. Elegant Rasboras will rarely reach their maximum size in home aquariums.

Spot-Tailed Rasbora (Rasbora caudimaculata)

ORIGINS: Southeast Asia, occurring on the Malay Peninsula, Sumatra, and Borneo.
SIZE: 4 3⁄4 in (12 cm).
DIET: Flake and live foods.
WATER: Temperature 68–77°F (20–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

These rasboras are generally smaller than Scissortail Rasboras, and their silvery body color also terminates in a deeply forked caudal fin that resembles a pair of scissors. Each lobe of the caudal fin has a colored area and ends in a dark tip. The slim body shape of these fish reveals their active nature. They can also jump effectively, which means that the aquarium or spawning tank should always be kept covered.

Slender Rasbora (Rasbora daniconius)

ORIGINS: Asia, from India and Sri Lanka, via Myanmar (Burma) and Thailand, to the Greater Sunda Islands.
SIZE: 4 in (10 cm).
DIET: Flake and live foods.
WATER: Temperature 75–79°F (24–26°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

The appearance of this species is not dissimilar to that of the Long-Band Rasbora, but its dorsal fin is set slightly farther back and its body color may be a little darker. Males have a yellow tinge to their fins and are slimmer than females, which swell noticeably with eggs. Spawning is reasonably easy to accomplish under favorable water conditions; this may entail dropping the pH slightly and raising the water temperature.

Redline Rasbora (Trigonopoma pauciperforatum)

ORIGINS: Southeast Asia, present on the Malay Peninsula and as far south as Sumatra.
SIZE: 3 in (7 cm).
DIET: Flake and live foods.
WATER: Temperature 73–77°F (23–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

The brilliant red stripe along each side of the body helps to sex these rasboras. When females swell with spawn, the stripe has a more curved appearance toward the rear of the body, but in the slimmer males it is always relatively straight. Compatibility between individuals can be an obstacle to successful breeding, but in a shoal the sexes will be able to pair naturally; paired fish remain in close contact with one another.

Narrow-Wedge Harlequin (Trigonostigma espei)

ORIGINSL Southeast Asia, where it is restricted to parts of Thailand.
SIZE: 1 3⁄4 in (4.5 cm).
DIET: Flake and live foods.
WATER: Temperature 73–82°F (23–28°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

Once regarded as a subspecies of the Harlequin Rasbora (see below), this fish is now considered to be a separate species. It is more colorful than the Harlequin, with males displaying an especially rich red coloration. Although the two fish have similar markings, the Narrow-Wedge has an extra black line at the back of the gills, while its black flank markings are less prominent. For breeding, house a single female and two males in the spawning tank, which should include broad-leaved plants such as cryptocorynes. Transfer the adults back to the main aquarium to rejoin the shoal as soon as spawning is finished.

Harlequin Rasbora (Trigonostigma heteromorpha)

ORIGINS: Southeast Asia, occurring in Thailand and Malaysia, and southward to the island of Sumatra.
SIZE: 2 in (5 cm).
DIET: Flake and live foods.
WATER: Temperature 73–77°F (23–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

This long-standing aquarium favorite has been popular with hobbyists for nearly a century, which is why it is sometimes simply referred to as “the Rasbora.” The dark, triangular-shaped marking on the rear part of the body, which tapers down the caudal peduncle to the base of the caudal fin, makes the Harlequin easy to recognize. Males are more colorful than females.

Hi-Spot Rasbora (Brevibora dorsiocellata)

ORIGINS: Southeast Asia, occurring throughout the Malay Peninsula and southward to Sumatra.
SIZE: 2 1⁄2 in (6.5 cm).
DIET: Flake and live foods.
WATER: Temperature 68–77°F (20–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful.

This golden-bodied fish has a black eyespot on its dorsal fin. A red, rather than yellow, tinge to the caudal fin indicates a male. The spawning tank should contain only about 6 in (15 cm) of water, and there should be marbles on the base. This will protect the eggs after spawning, because the fish will have less time to eat them before the eggs fall out of reach. If the female is placed in the tank a few days in advance, spawning should occur quite rapidly. The eggs hatch in a day.

White Cloud Mountain Minnow (Tanichthys albonubes)

ORIGINS: Asia, occurring in the White Cloud Mountain region around Canton, China.
SIZE: 1 1⁄4 in (4.5 cm).
DIET: Flake and live foods.
WATER: Temperature 64–77°F (18–25°C); soft (50 mg/l) and acidic (pH 6.0–6.5).
TEMPERAMENT: Peaceful and social.

The original form of the White Cloud Mountain Minnow has pale yellow edges on its fins, but a strain found in Hong Kong, which developed from aquarium escapees, displays red fin-edging. Females are not as brightly colored as males. These rasboras can be kept in much cooler waters than most, down to 40°F (4.5°C), but for breeding the optimum temperature is about 70°F (21°C). They spawn among vegetation, with the eggs hatching just over a day after being laid.

GROUP DYNAMICS

The majority of rasboras are shoaling fish, and if they are kept singly in the aquarium, they become shy and nervous. There appears to be some recognition between members of a shoal, since new individuals added to an aquarium containing an established group are unlikely to be accepted readily by the rest of the shoal. As a result, the newcomers may form a separate group, but there is rarely any conflict between the shoals. Changing the decor of the tank just before the newcomers are introduced seems to improve the chances that the fish will integrate.

RASBORA JAW STRUCTURE

Many cyprinids have downward-pointing mouthparts adapted for feeding on the substrate. Rasboras are not substrate feeders, however, but quick, agile, sharp-eyed predators that seek their food in the middle and upper layers of the water. As a result, their lower jaw curves up, rather than down, as seen here on this Narrow-Wedge Harlequin (see opposite). This jaw structure makes it easier for the rasboras to snatch aquatic invertebrates swimming just above them in the water and also to grab any flying insects that may settle on the surface.

[Ebook] Encyclopedia of Aquarium & Pond Fish – Directory of Freshwater Fish – Cyprinids – Rasboras