Chilatherina bleheri (Bleher's Rainbowfish)

Overview

Bleher's Rainbowfish (Chilatherina bleheri) is one of the most visually spectacular members of the Melanotaeniidae family. Discovered by the famous explorer Heiko Bleher in 1982, this species has captivated the aquarium hobby with its unique two-toned body. They are energetic, hardy when kept in optimal conditions, and make a brilliant centerpiece for a large, planted community aquarium.

Distribution and Habitat

This species is endemic to Lake Holmes (also known as Danau Bira) and its surrounding tributary streams in the lower Mamberamo River basin of Papua, Indonesia. They are typically found in clear, shallow waters over rocky substrates, often congregating around submerged vegetation, fallen branches, and the sunlit shores where they can easily hunt for insects and small aquatic organisms.

Description of Bleher's Rainbowfish

Body shape:

They possess an elongated, laterally compressed body that deepens as the fish matures. Adult males develop a significantly deeper chest and a slightly arched back compared to the more streamlined females.

Color:

Their most defining feature is their striking split coloration. The anterior (front) half of the body gleams with iridescent silver, green, and blue hues, while the posterior (back) half transitions into a vivid red, orange, or deep yellow. Males display the most intense colors, especially during the morning spawning rituals.

Barbels:

Like all rainbowfish, they do not possess barbels.

Snout:

They have a relatively pointed snout with a small, terminal mouth adapted for feeding on insects at the water's surface as well as mid-water zooplankton.

Eyes:

Their eyes are large and alert, featuring a dark pupil surrounded by a silvery-gold iris, which aids them in spotting prey in brightly lit, clear waters.

Fins:

They feature two dorsal fins, a characteristic of the rainbowfish family. The fins are often translucent but heavily tinged with the red or orange coloration of their posterior body, with males possessing longer, more pointed fin rays.

The Tail:

The caudal (tail) fin is moderately forked and prominently colored in deep red or orange, providing strong propulsion for their active swimming habits.

Temper

Bleher's Rainbowfish are extremely peaceful and good-natured. They do not bother other tank mates, though their high energy and rapid swimming can sometimes stress very shy or slow-moving species.

Sociality

This is a highly social, schooling species. They must be kept in groups of at least 6 to 8 individuals, with a recommended ratio of more females than males to disperse the males' vigorous breeding pursuits. A larger school will result in better coloration and more natural behaviors.

Activity

They are highly active swimmers that occupy the middle and upper levels of the water column. They are almost constantly on the move during daylight hours, darting around the tank and engaging in playful sparring or displaying.

Keeping and Caring for Bleher's Rainbowfish

Tank size:

Because of their size and active swimming style, a minimum tank length of 120 cm (48 inches) and a volume of at least 200 liters (55 gallons) is required to provide them with adequate open swimming space.

Water Parameters:

Temperature

They prefer slightly warmer water than some other rainbowfish, thriving between 25-30°C (77-86°F).

pH

A neutral to slightly alkaline pH is ideal, ranging from 7.0 to 8.0.

Hardness

They do best in moderately hard water, with a general hardness (dGH) of 10 to 20.

Ammonia, Nitrite, Nitrate

Ammonia and Nitrite must always be at 0 ppm. Nitrates should be kept as low as possible, ideally below 20 ppm, through regular water changes, as they are sensitive to declining water quality.

Lighting

Moderate to bright lighting is recommended. Not only does it encourage the growth of aquatic plants, but it also highlights the breathtaking iridescence of the fish's scales.

Water flow

A moderate water flow mimics the currents of their natural habitat and provides them with the exercise they need. A good quality canister filter can provide the right amount of movement and oxygenation.

Decorations and Plants

The tank should feature dense plantings along the back and sides, leaving a large, unobstructed swimming area in the middle. Dark substrates and the addition of driftwood or rocks will help make their vivid colors pop.

Diet

In the wild, they are omnivores feeding on insects, small crustaceans, and plant matter. In the aquarium, they readily accept high-quality flake and pellet foods. Their diet should be supplemented with live or frozen foods such as bloodworms, daphnia, and brine shrimp, as well as spirulina or blanched vegetables to ensure optimal health and coloration.

Some Feeding Tips

Because they have relatively small throats, ensure that pellets or granules are appropriately sized. Feed them small amounts 2 to 3 times a day rather than one large meal, which mimics their natural continuous foraging behavior.

Breeding

Breeding is relatively straightforward. They are continuous egg scatterers. To breed them, set up a dedicated breeding tank with slightly alkaline water and add spawning mops or fine-leaved plants like Java Moss. Condition the breeders with plenty of live foods. Males will display intensely to attract females, who will lay a few eggs each day. Since parents may eat the eggs, the spawning mop should be removed daily to a separate rearing tank. Eggs hatch in about 7 to 10 days, and the tiny fry will require infusoria or liquid fry food until they are large enough to accept newly hatched brine shrimp.

Conclusion

Bleher's Rainbowfish is a truly magnificent species that brings unparalleled color and lively energy to the freshwater aquarium. While they require a sizable tank and pristine water conditions, their peaceful nature and the stunning visual reward of a mature, flashing school make them a highly prized choice for dedicated aquarists.