Order Characiformes
Family Hepsetidae
Genus Hepsetus, African Pike Characin — Hepsetus.
— African Pike — Hepsetus odoe [Bloch, 1794]. Synonyms: Hydrocyonoides cuvieri, odoe; Salmo, Sarcodaces, Xiphorhamphus odoe. English: African Pike Characoid, Kafue Pike. Its distribution covers almost all tropical Africa, excluding the Nile basin. 60 cm. Their scales are embossed, cycloid, and the elongated jaws are armed with strong teeth.
The body is silvery with a brownish-green back and spots on the dorsal and caudal fins. Coloration is greenish-olive with silvery sparkles and a honeycomb pattern on the scales. The throat and lower belly are white. Fins are speckled with a milky-white border along the outer rays. The tail is two-lobed with a deep notch, and the iris is reddish-brown. Males are brighter and slimmer than females.
Predators, growing very fast. Requires a large aquarium and intensive feeding with live fish. Driftwood and smooth stones are used to decorate the aquarium, along with dense vegetation in some areas, and floating plants can be added on the surface. Powerful and effective biological and mechanical filtration is a must, as the fish produces a lot of waste.
Small fish will be chased until all are eaten. For feeding, shrimp, worms, pupae, mussels, etc., are used. Almost all fish are imported at a juvenile age. They mature in their 3rd year of life. They build a bubble nest 17 cm in diameter and 9 cm high. The eggs are guarded by one or both parents. They live for 5 years. pH 6–7.5; dH 8–18°; T 25–28°C.
Identification: African Pike — Hepsetus odoe.
Family Erythrinidae
Predatory fish. A pugnacious temper and high territoriality often result in only one dominant individual remaining.
Genus Erythrinus.
— Trahira, Rainbow Wolf Fish — Erythrinus erythrinus [Bloch & Schneider, 1801]. Synonyms: Erythrinus brevicauda, longipinnis, salmoneus, Synodus erythrinus. English: Rainbow Wolf Fish. Peru, Guiana, Venezuela, Brazil, Trinidad and Tobago. 20 cm. They have a modified swim bladder that acts as an accessory respiratory organ, allowing the fish to survive in oxygen-depleted and stagnant waters. They are known to travel overland for short distances in search of new habitats when seasonal waters begin to dry up.
These fish have an elongated, curved, cylindrical body with powerful jaws. They have variable color and pattern depending on their habitat locality. Juveniles have red, yellow, and even purple spots on their sides against a general brown or maroon body. Unpaired fins can be bright red, yellow, or white. There is a variant from Peru that has a bright orange belly.
Active, tireless predators, distinguished by a love for meaty food. They create a real “feast of death” in any aquarium; it is best to keep them alone in tanks with a volume of at least 200 liters. They usually hide among plants, waiting for suitable prey to strike; powerful fins ensure the lightning speed of their lunge, and smaller fish will be eaten. Fish that do not challenge their territory and do not fit in their mouths are generally ignored. All movements of the fish are focused, elegant, devoid of unnecessary fuss.
An aquarium with plenty of hiding places made of stones and driftwood; they like ceramic tubes and floating plants on the surface. Under bright lighting or in the absence of hiding places, they will spend most of their time hiding. The aquarium lid must fit tightly, as they can escape if given the opportunity. They adapt very well and are unpretentious regarding the chemical composition of the water.
In the aquarium, their diet should consist of meaty foods such as earthworms, shrimp, mussels, and fish meat. They usually refuse dry food, although some individuals accept it over time. Be careful during aquarium maintenance, as their mouths are filled with sharp teeth, and the fish show no fear, attacking any new object that appears in the tank, such as siphon tubes, nets, or the owner’s hands. pH 5.5–7.5; dH 2–25°; T 22–26°C.
Genus Hoplias.
— Malabar Hoplias, Trahira, Wolf Fish — Hoplias malabaricus [Bloch, 1794]. Synonyms: Erythrinus macrodon, trahira, Esox malabaricus, tararira, Hoplias malabarica, Macrodon ferox, malabaricus, tareira, Synodus palustris. English: Haimara, Tararura, Tiger Characin, Trahira, Wolf Fish. South America, from Panama to Brazil. 45 cm. Cylindrical body, large head and mouth with powerful canine-like teeth on robust jaws. The skin is covered with cycloid scales and an abundant layer of mucus that protects against parasites such as leeches.
Body coloration can vary from mottled gray to brown, sometimes almost black; the back is spotted, and the belly is yellowish-white. Males are brighter, slimmer, and more streamlined than females, with a fan-like dorsal fin. During the spawning season, their coloration becomes lighter, and the dark striping almost completely disappears. The flanks of males cast silver, while females cast gold. Only the dark “confetti” on the fins becomes more contrasting, and females develop a pear-shaped ovipositor. Young fish are light brown with a reddish tint and long dark stripes, featuring bright yellow or green eyes. With age, the reddish color decreases, and the dark stripes transition into a series of dark spots.
This large, bottom-dwelling predator easily reaches half a meter in length. Touching trahiras is not recommended: their bites are painful and take a long time to heal. The fish eats anything it can catch, and the size of the prey can almost reach the size of the fish itself. They cannot be kept in the same aquarium with other species regardless of their size. Various hiding places (stone grottoes, drainage pipes, driftwood piles) and isolated clumps of broad-leaved plants are necessary. Intraspecific aggression is characteristic of them. Even juveniles behave aggressively toward one another. Minor injuries sustained in territorial fights usually heal quickly.
Active at dusk and at night, very lazy and moving only for food. Due to the presence of a specific accessory respiratory organ, they adapt to almost any reasonable maintenance conditions, but of course, a powerful filtration system is still required. Breeders become sexually mature after three years, having reached at least 20 cm in length. They spawn on the substrate. They place the nest in a dim corner among vegetation or near fibrous tree roots. The male zealously guards the offspring, rushing even at the shadow of a hand approaching the glass. They live up to 15 years. T 22–25°C; dH up to 20°; pH 6.5–8.0.
Genus Hoplerythrinus.
— Golden Wolf Fish — Hoplerythrinus unitaeniatus [Spix & Agassiz, 1829]. Synonyms: Erythrinus balteatus, kessleri, salvus, unitaeniatus, vittatus, Pseuderythrinus rosapinnis. English: Aimara, Golden Trahira. Venezuela, Guiana, Ecuador, Peru, Brazil, Bolivia, Argentina, often found in very shallow water or among vegetation near the surface. 25 cm. The body is cylindrical with a rounded head and a large mouth. The adipose fin is absent.
Coloration is brown or gray with a characteristic black spot in the upper region of the gill cover; two or three dark lines run from the eyes to the gill cover. The body is crossed by a series of dark, irregular vertical stripes that are darker toward the rear. Males have reddish first fin rays. They can venture onto land in search of new habitats when floodwaters begin to dry up or when food is scarce. Similar to Hoplias malabaricus, but more active and aggressive.
An aquarium with plenty of floating vegetation; under bright lighting or in the absence of hiding places, it will spend most of its time hiding. It leads a bottom-dwelling lifestyle, rising to the surface only for a gulp of air. It must be provided with numerous hiding places and shelters. The aquarium lid must fit tightly, as it can escape if given the opportunity.
Suitable for various water conditions. The fish eats anything it can catch. It must not be kept in the same aquarium with other species regardless of their size. It is advisable to keep it alone. In captivity, they accept aquarium foods, but live foods (invertebrates and small fish) must be provided on a regular basis. pH 6–7.5; dH 4–25°; T 23–27°C.
Genus Derhamia, Genus Lebiasina, Genus Piabucina.
Hemiodus gracilis, quadrimaculatus, unimaculatus. 
