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

Directory of Freshwater Fish

Rainbowfish

The brilliantly colored rainbowfish have grown rapidly in popularity in recent years as they have become more readily available. A significant number of new species have been discovered and introduced to the aquarium hobby since the 1980s, and there are almost certainly others awaiting discovery, especially in New Guinea. Local populations within a species may look very different, and it is important to maintain their individual features. Unfortunately, some rainbowfish breeders are now hybridizing their stock in an attempt to create even more colorful offspring. There is some evidence that these fish may themselves occasionally hybridize in the wild.

Threadfin Rainbowfish (Iriatherina werneri)

• ORIGINS: New Guinea, between the Fly and Merauke rivers; also occurs in northern Australia.
• SIZE: 2 in (5 cm).
• DIET: Eats both prepared diets and small live foods.
• WATER: Temperature 72–84°F (22–29°C); soft (50–100 mg/l) and acidic to alkaline (pH 6.5–7.5).
• TEMPERAMENT: Peaceful.

Mature males display with their elaborate fins during the courtship ritual, holding them erect and then flicking them up and down. An aquarium planted with fine-leaved vegetation is essential for spawning; females lay over the course of several days. The eggs can take a week or longer to hatch, and the fry can be reared on tiny rotifers. Adult fish prefer to eat small live foods, but will take flake powdered onto the water’s surface.

Bowfish (Bedotia madagascariensis)

• ORIGINS: East Africa, where it is found only in upland areas on the island of Madagascar.
• SIZE: 6 in (15 cm).
• DIET: Eats both prepared diets and small live foods.
• WATER: Temperature 68–75°F (20–24°C); hard (150–200 mg/l) and neutral (pH 7.0).
• TEMPERAMENT: Peaceful.

The male bowfish is multicolored, with shades of blue apparent on the flanks; the female is yellow and has a rounded, rather than jagged, dorsal fin. Bowfish thrive in groups and will not eat their eggs (which become tangled among vegetation) or their fry. Young bowfish are unusual in that they swim immediately after hatching, initially in a somewhat vertical stance, although they soon adopt a more horizontal posture.

Salmon-Red Rainbowfish (Glossolepis incisus)

• ORIGINS: New Guinea, where it is restricted to Lake Sentani in Irian Jaya.
• SIZE: 6 in (15 cm).
• DIET: Small live foods preferred.
• WATER: Temperature 77–86°F (25–30°C); hard (150–200 mg/l) and neutral (pH 7.0).
• TEMPERAMENT: Peaceful.

Sexing is straightforward because the male is salmon-pink while the female is yellowish and olive-green. Juveniles tend to resemble adult females in appearance, but the young males change color once they are about 2 in (5 cm) in length. In the wild, Salmon-Red Rainbowfish feed on small invertebrates and associate in areas of aquatic vegetation. Females lay batches of between 100 and 150 eggs, which usually hatch within 10 days.

Bleher’s Rainbowfish (Chilatherina bleheri)

• ORIGINS: New Guinea, occurring in Lake Holmes and associated streams, and in Mamberamo, Irian Jaya.
• SIZE: 4 3⁄4 in (12 cm).
• DIET: Prefers small live foods.
• WATER: Temperature 77–86°F (25–30°C); hard (150–200 mg/l) and neutral (pH 7.0).
• TEMPERAMENT: Peaceful.

Sexing is straightforward because the male is salmon-pink while the female is yellowish and olive-green. Juveniles tend to resemble adult females in appearance, but the young males change color once they are about 2 in (5 cm) in length. In the wild, Salmon-Red Rainbowfish feed on small invertebrates and associate in areas of aquatic vegetation. Females lay batches of between 100 and 150 eggs, which usually hatch within 10 days.A deep-bodied appearance is a characteristic feature of Bleher’s Rainbowfish, with males attaining a larger size than females and being more vibrantly colored. The front of the body is an iridescent silvery-green, becoming yellowish and then purplish-red toward the tail. It is possible to tell when males are in spawning condition because they display a yellow-orange stripe on the forehead. The species is named after Heiko Bleher, a well-known German aquarist.

Australian Blue-Eye (Pseudomugil signifer)

• ORIGINS: Australia, from northern Queensland southward to Narooma in New South Wales.
• SIZE: 2 1⁄2 in (6 cm).
• DIET: Eats both prepared diets and small live foods.
• WATER: Temperature 59–82°F (15–28°C); soft (50–100 mg/l) and acidic to alkaline (pH 5.5–7.8).
• TEMPERAMENT: Territorial when spawning.

These rainbowfish vary significantly in appearance throughout their range. Northern specimens have very long filaments on their dorsal and anal fins and are larger than their southerly counterparts. The males’ coloration changes with age and becomes more vibrant when they are in spawning condition. Females are less colorful than males. Australian Blue-Eyes are found in fresh and brackish waters, and even in the sea in some areas.

Forktailed Blue Eye (Pseudomugil furcatus)

• ORIGINS: Eastern New Guinea, occurring between Collingwood and Dyke Ackland Bays.
• SIZE: 2 1⁄2 in (6 cm).
• DIET: Small live foods preferred.
• WATER: Temperature 73–79°F (23–26°C); soft to hard (50–150 mg/l) and neutral to alkaline (pH 7.0–8.0).
• TEMPERAMENT: Peaceful.

The male Forktail, shown below, is more brightly colored than the female, has a larger dorsal fin, and often shows red on its pelvic and pectoral fins. Forktails occur in clear, fast-flowing streams where there is a good covering of aquatic plants, so their tank should be well planted but include clear areas for swimming. Spawning may occur on the substrate or among plants. The eggs develop slowly and can take up to two weeks to hatch.

Celebes Rainbowfish (Marosatherina ladigesi)

• ORIGINS: Indonesia, where it occurs on the island of Sulawesi (formerly known as Celebes).
• SIZE: 3 in (7.5 cm).
• DIET: Eats both prepared diets and small live foods.
• WATER: Temperature 68–82°F (20–28°C); hard (150–200 mg/l) and neutral to alkaline (pH 7.0–7.5).
• TEMPERAMENT: Peaceful.

Male Celebes Rainbowfish are more colorful than females and have longer fin rays. These fish are sensitive to water quality, so it is vital to check the parameters to which they are acclimatized. Change conditions slowly, by making a partial water change of 25 percent of the tank’s volume each week. Under favorable conditions, adults may spawn almost nonstop for months, although they often eat their eggs. Hatching takes up to 11 days.

SPLIT-FIN DESIGN

One of the most distinctive characteristics of this group of fish is the structure of the dorsal fin, which is divided into two parts, with an obvious gap between. This arrangement enables each part of the dorsal fin to be raised or lowered largely independently of the other. It is usually the front part of the fin that is kept lowered, probably so that it does not interfere with the swimming ability of the rainbowfish. This suggests that the function of the split fin is primarily for display. The shape of the fin can also be useful in distinguishing between the sexes. The rear part of the second dorsal generally tapers to a point in the males, although this characteristic is less evident in the rainbowfish of Lake Tebera, New Guinea.