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

Directory of Freshwater Fish

Characoids

It is surprisingly difficult to describe exactly what defines a characoid, in spite of the fact that many of them are popular aquarium fish. While they usually have teeth, they are not the only group of fish with this characteristic. Most characoids have a small, remote fin located on the back, just in front of the caudal fin. This fin, which lacks any rays, is called an adipose fin, but then again, not every member of the group displays this feature. Although the majority of characoid species are of New World origin, the group is also well represented in Africa.

Golden Pencilfish (Nannostomus beckfordi)

• ORIGINS: Northern South America, in the central Amazon region, the Rio Negro, and Guyana.
• SIZE: 3 in (7.5 cm).
• DIET: Prepared diets, plant matter, and live foods.
• WATER: Temperature 75–82°F (24–28°C); hard (150–200 mg/l) and acidic to neutral (pH 6.0–7.0).
• TEMPERAMENT: Social, peaceful, and timid.

Sky-blue tips to the clear ventral fins are a feature of these fish, which also have a broad dark stripe along the body, with a red line above, and perhaps a hint of gold in between. Nannostomus pencilfish have small mouths, and they may choke or simply go hungry if their food is too large. Flake and small live foods such as daphnia are ideal. Sex can be determined by the shape of the anal fin, which is more rounded in males.

Spotted Headstander (Chilodus punctatus)

• ORIGINS: Found in northeastern South America, including parts of Guyana.
• SIZE: 4 3⁄4 in (12 cm).
• DIET: Live foods preferred.
• WATER: Temperature 75–82°F (24–28°C); soft (50–100 mg/l) and acidic to neutral (pH 6.5–7.0).
• TEMPERAMENT: Social, peaceful, and often retiring.

The Spotted Headstander displays rows of dark, similar-sized spots, with a more definite line running through the eye to the tail. Some individuals have a more golden background color than others. The spotted patterning is replaced by black blotches behind each eye when the fish come into spawning condition. Like other headstanders, these fish often hang in the water at an angle of approximately 45°, which explains the common name. Filtration through peat is recommended (see p.46). Spotted headstanders can be bred successfully in the home aquarium.

High-Backed Headstander (Abramites hypselonotus)

• ORIGINS: South America, occurring in the Amazon, Orinoco, and Paraguay river basins.
• SIZE: 5 in (12.5 cm).
• DIET: Vegetable matter essential.
• WATER: Temperature 75–82°F (24–28°C); hard (100–150 mg/l) and acidic to neutral (pH 6.0–7.0).
• TEMPERAMENT: Intolerant of its own kind.

The body of this fish is marked by broad, blackish, vertical bands. The silvery background becomes more yellowish on the upperparts. The young do not display the high back, which is limited to the adults. Decorate the aquarium with rockwork and bogwood. Choose plants carefully because they are likely to be eaten, or use plastic plants instead. Cover the tank, because these headstanders will jump readily. Their intolerance makes pairing difficult.

Silver Hatchetfish (Gasteropelecus sternicla)

• ORIGINS: South America, in Surinam and Guyana, plus southern tributaries of the Amazon.
• SIZE: 2 1⁄2 in (6.5 cm).
• DIET: Live foods preferred, plus flake.
• WATER: Temperature 73–81°F (23–27°C); hard 100–150 mg/l) and acidic to neutral (pH 6.0–7.0).
• TEMPERAMENT: Peaceful and social, but nervous.

The Silver Hatchetfish has a distinguishing black stripe on its rear half that extends to the caudal peduncle. Males look slimmer than females when viewed from above These fish prey on invertebrates that congregate near the surface, such as mosquito larvae, and feed eagerly on wingless fruit flies or baby crickets dropped onto the water. Make sure the water surface is not blocked by floating plants

Marbled Hatchetfish (Carnegiella strigata)

• ORIGINS: Northern South America, occurring in Guyana and the middle Amazon.
• SIZE: 2 1⁄2 in (6 cm).
• DIET: Small live foods and flake.
• WATER: Temperature 75–82°F (24–28°C); soft (50–100 mg/l) and acidic (pH 6.0).
• TEMPERAMENT: Social and inoffensive

This hatchetfish has silver-and-black marbling and a yellowish line from the eye to the caudal peduncle. It is easy to breed if regularly given live foods. Use blackwater extract to help create suitable water conditions. The eggs, laid among the roots of floating plants, fall to the base of the tank. Give the fry infusoria or suitable fry food once they are free-swimming at about five days old and brine shrimp after a week or more.

Dwarf Hatchetfish (Carnegiella myersi)

• ORIGINS: South America, occurring in the Rio Ucayali, Peru, and also in Bolivia.
• SIZE: 1 in (2.5 cm).
• DIET: Small live foods and flake.
• WATER: Temperature 73–79°F (23–26°C); soft (50–100 mg/l) and acidic (pH 6.0).
• TEMPERAMENT: Social and inoffensive

The internal organs of this hatchetfish are visible through its semitransparent body. There is a black stripe running from the eye to the tail. The Dwarf is the smallest of all the hatchetfish, but it has a lifestyle similar to its larger relatives, living and feeding near the surface. It is relatively trustworthy with the fry of other fish and can sometimes even be housed in rearing tanks.

FLYING HATCHETS

The aerodynamic shape of hatchetfish, with the deep, boatlike keel, means that these fish are sufficiently streamlined to be able to leap out of the water without difficulty, as shown in this picture. Their flat topline reflects the fact that hatchetfish normally lurk just below the surface, grabbing surface-swimming invertebrates and others that touch down momentarily on the water. The upturned mouth is another adaptation to surface feeding. When hatchetfish are viewed from above, their flat body shape makes them difficult to spot, even near the surface, because so little of the body is visible. They have sharp eyesight to help them catch prey and avoid predators. On occasion, usually to escape would-be predators approaching them in the water, these fish will take to the air. The flapping movements of their pectoral fins are powerful enough to keep them airborne, enabling them to cover distances of up to 4 ft (1.2 m) before reentering the water. While in the air, they use their caudal fin to provide them with some directional guidance. It is essential that an aquarium housing hatchetfish is kept covered, even when it is being serviced, because otherwise they are likely to leap out into the room.

Black-Banded Pyrrhulina (Copella nigrofasciata)

• ORIGINS: Eastern South America, found in Brazil in the vicinity of Rio de Janeiro.
• SIZE: 2 1⁄2 in (6 cm).
• DIET: Flake and small live foods.
• WATER: Temperature 70–77°F (21–25°C); soft (50–100 mg/l) and acidic (pH 6.0).
• TEMPERAMENT: Peaceful.

Subdued lighting emphasizes the color of these pyrrhulinas, in particular the pale blue stripes on the sides of the body. A narrow black line runs through the eye. Sexing is straightforward, since the fins are more pointed and brightly colored in the male, shown above. A pair will spawn on a leaf, which is first carefully cleaned by the male. The eggs hatch after about a day, and the fry are free-swimming by the time they are 5 days old.

Swordtail Characin (Corynopoma riisei)

• ORIGINS: Found in northern South America, where it occurs in Colombia’s Rio Meta.
• SIZE: 2 1⁄2 in (6.5 cm).
• DIET: Prepared foods and small live foods.
• WATER: Temperature 72–82°F (22–28°C); soft (50–100 mg/l) and neutral (pH 7.0).
• TEMPERAMENT: Peaceful and social.

Like the female, pictured below, the male is silvery in color but has a swordlike extension on the lower lobe of the caudal fin and a filament on each gill cover, which is probably used to steer the female into position for mating. Fertilization is internal, and the eggs are laid in the male’s absence. Hatching occurs up to 36 hours later, and the young Swordtails can be reared on fry food, followed by brine shrimp.

Splashing Tetra (Copella arnoldi)

• ORIGINS: South America, occurring in Guyana, in the lower part of the Amazon basin.
• SIZE: 3 1⁄4 in (8 cm).
• DIET: Prepared foods and small live foods.
• WATER: Temperature 77–84°F (25–29°C); soft (50–100 mg/l) and acidic (pH 6.0).
• TEMPERAMENT: Peaceful and social.

Male Splashing Tetras are larger than females, with red markings on the caudal fin. Because of the athletic behavior of these fish, keep the aquarium covered and the water level reasonably low. A spawning pair will jump up and deposit as many as 15 small batches of eggs on a broad leaf protruding above the water line, or even on the glass of the tank. The male keeps the eggs moist by splashing them with its tail every 30 seconds or so, continuing until they hatch about three days later.

Red-Spotted Copeina (Copeina guttata)

• ORIGINS: Northern South America, occurring widely throughout the Amazon basin.
• SIZE: 6 in (15 cm).
• DIET: Prepared foods and small live foods.
• WATER: Temperature 73–84°F (23–29°C); soft (50–100 mg/l) and acidic (pH 6.0).
• TEMPERAMENT: May be aggressive when spawning.

The pattern of red spots is most apparent in the male, shown here; the male also displays an enlarged upper lobe on the caudal fin and has a stronger body color. These fish can be disruptive in the tank, especially at the start of the spawning period, when the male may chase its intended partner relentlessly. The eggs are laid in batches in a scrape in the substrate. They are guarded by the male, who also oxygenates them by fanning them with his fins. The young, which emerge after about two days, need a fry food once they are free-swimming. For breeding, ensure that there is a soft, sandy substrate that the male can excavate. Include a clear digging area so that plants are not uprooted by the male’s actions. Raising the water temperature is a proven spawning trigger.

Hockey Sticks (Thayeria boehlkei)

• ORIGINS: Northern South America, in the Peruvian part of the Amazon basin, and in Brazil’s Rio Araguaia.
• SIZE: 3 in (7.5 cm).
• DIET: Prepared foods and small live foods.
• WATER: Temperature 73–84°F (23–29°C); soft (50–100 mg/l) and acidic (pH 6.0).
• TEMPERAMENT: Peaceful and social.

Hockey Sticks have a black stripe that extends from behind the gills back to the caudal peduncle and then diverts down across the lower lobe of the caudal fin. A faint golden line running beneath this stripe is also apparent. In the Penguin Fish (T. obliqua), the black stripe is shorter and reaches only as far as the base of the dorsal fin. It is essential to make a partial water change every two weeks in order to prevent any harmful nitrate buildup.

Long-Finned African Tetra (Brycinus longipinnis)

• ORIGINS: Western Africa, present in the Niger delta, Ghana, Sierra Leone, and Togo.
• SIZE: 5 in (13 cm).
• DIET: Prepared foods and small live foods.
• WATER: Temperature 73–79°F (23–26°C); soft (50–100 mg/l) and acidic (pH 6.5).
• TEMPERAMENT: Peaceful and social

A prominent black stripe along the lower part of the caudal peduncle helps to identify this characoid. The remainder of its body has a silvery-green hue, which is most apparent in low-level lighting. This nervous yet active fish should be housed in small groups, with spacious surroundings to provide plenty of swimming space and floating plants on the surface to provide some cover. Only a mature male—the upper fish of the pair pictured here—has extended dorsal fin rays. Good water quality serves to improve the males’ coloration. Avoid nitrate accumulation by carrying out partial water changes every two weeks or so. Long-Finned African Tetras require a separate spawning tank, with vegetation among which they can scatter their eggs (an artificial spawning mop may be used instead of plants). Hatching can take as long as six days.

HANGING AROUND

Penguin fish have such a strong shoaling instinct that they even rest together as a group, hanging at an angle in the water with all the fish facing the same direction, as illustrated by the group of Hockey Sticks below. In this position, the mass of stripes makes the shoal resemble underwater vegetation when viewed from a distance, camouflaging the fish in reedy stretches of water where many shoots grow up toward the surface. The name “penguin fish” alludes to the way in which penguins move on land, with their bodies leaning slightly forward.

Watermelon Fish (Chalceus erythrurus)

• ORIGINS: Northern South America, present in the Amazon basin and extending north to the Guianas.
• SIZE: 10 in (25 cm).
• DIET: Prepared foods and live foods.
• WATER: Temperature 73–82°F (23–28°C); soft (50–100 mg/l) and acidic (pH 6.0).
• TEMPERAMENT: An active predator.

The slim, silvery body and reddish-pink caudal fin are characteristic features of the Watermelon Fish. In some populations, the other fins are yellowish. This is one of the larger and more predatory characoid species, so any tankmates should be chosen carefully. It may be necessary to wean this fish off live foods; thawed items are likely to prove more palatable than freeze-dried alternatives. Nothing is known about the breeding habits of Watermelon Fish.

Striped Headstander (Anostomus anostomus)

• ORIGINS: Northern South America, from Colombia down the Amazon to Manaus; also found in the Orinoco.
• SIZE: 7 in (18 cm).
• DIET: Prepared foods, live foods, and vegetable matter.
• WATER: Temperature 73–82°F (23–28°C); soft (50–100 mg/l) and slightly acidic (pH 6.5).
• TEMPERAMENT: Can be aggressive.

The attractive patterning of these headstanders (so-called because they often rest with the head pointing downward) consists of alternating stripes of black and yellow. Striped Headstanders need powerful filtration and good lighting to encourage algal growth, which makes up part of their natural diet. Retreats in the form of rocks and bogwood are also important. Aggression levels will be lower if these fish are kept in shoals.