Order Characiformes ( Characiformes )
Family Crenuchidae ( Crenuchidae )
Subfamily ( Crenuchinae )
Genus Crenuchus — Crenuchus.
They need a large aquarium. They do not lead as predatory a lifestyle as commonly attributed to them. They live peacefully and hide in distant corners of the aquarium when their tank mates show excessive activity. During the spawning period, males establish territories from which they drive away other fish. At the same time, they behave much more strictly towards conspecifics than towards fish of other species. They pay no attention at all to fish in the upper water layers. The aquarium should be heavily planted, and hiding places must be provided. Sexual dimorphism in adults is simple — males have more intense coloration and greatly enlarged dorsal and anal fins.
— Sailfin Characin — Crenuchus spilurus [Gunther, 1863]. (Eng. Sailfin Characin, Tetra). Widely distributed, its range includes most of the Amazon basin in Guyana and Guiana. Male 7 cm, female 5 cm. An elongated fish with a somewhat humped back. Beige-yellow with faintly reticulated scales and a golden streak along the body. Males are larger with a high dorsal fin and an elongated anal fin, adorned with a red reticulated pattern, and a large black spot at the base of the tail.
The dorsal fin in males has a filamentous ending. Fins are iridescent, transparent with small spots. Females are smaller with normal fins. Numerous geographic forms exist, some of which differ significantly in pattern and body coloration.
Displays behavior more reminiscent of dwarf cichlids. They have a rather large mouth, so keeping them in the same aquarium with smaller fish can be intimidating. Despite their predatory appearance, these fish can be kept in a community aquarium with other similarly sized fish. Males are strictly territorial. Having claimed a territory 20-30 cm in diameter, in the center of which there is a secure hiding place (a cave, half a coconut shell, or a suitable driftwood), they drive away other males of their species, and during the breeding period, they tolerate no extraneous fish in their territory at all.
If there is enough free space, they should be kept only as single pairs or in a harem consisting of one male and 2-3 females. Timid, non-competitive with active fish. Dense vegetation is required, including floating plants in which they can hide. Place plenty of hiding places made of rocks and driftwood in the aquarium. They only need soft, acidic, and clean water. Filtration is preferably done using peat.
Eggs are spawned in caves. The male cares for the clutch. The appearance of the fry undergoes a true metamorphosis. The head shape changes the most noticeably. Up to 2.5 cm in length, the head remains rounded and the mouth relatively small. The head characteristic of adults, featuring a somewhat slanted mouth and thick lips, develops later. Mostly imported from the wild. Lifespan up to 4 years. pH 5.0-6.5; dH 2-8°; T 24-26°C.
Identification: Sailfin Characin — Crenuchus spilurus.
Genus Poecilocharax — Poecilocharax.
For experienced aquarists only! When acquiring Poecilocharax from the trade, it is important to ensure that the fish have a straight belly area; otherwise, the fish typically die, even despite good feeding. Wild-caught fish require live food. Considerable patience will be required to transition them to other foods. The pH level must be checked regularly to prevent severe fluctuations.
During the acclimatization of the fish, lighting should not be too bright. Feed with live food or small portions of frozen foods, which Prachtsalmler eagerly eat even after the acclimatization phase. They stay near the bottom and occupy small territories within a radius of which they move. They can often be seen standing motionless between plants or tree roots.
Unlike many other characids, they are not schooling fish. Therefore, it is quite possible for them to live in pairs. Naturally, males display their amazingly beautiful fins to the female. They defend their territories against conspecifics, but not against fish of other species. Fighting males threaten each other with spread fins and wide-open mouths.
If no winner is determined, a fight may ensue, which frequently results in damage to the dorsal fin. Driftwood, rounded boulders, and floating plants with thread-like roots serve as hiding places. For successful maintenance, the fish require very soft, acidic, and nitrate-free water. A peat filter is mandatory and must be cleaned frequently.
— Poecilocharax bovalii — Poecilocharax bovalii [Eigenmann, 1909]. Guyana, Brazil. 5 cm. Males have noticeably enlarged dorsal and anal fins. Its caudal fin is bright red and speckled with light flecks. The female is fuller, paler, and smaller than the male. This is a bottom-dwelling fish, unfortunately very timid. The aquarium must be heavily planted, and hiding places must be provided. Very difficult to keep. Prefers live foods. pH 5.5-7.0; dH up to 8°; T 23-27°C.
— Black Darter Tetra — Poecilocharax weitzmani [Gery, 1965]. (Eng. Black Darter Tetra, Black Morpho Tetra). Brazil, Colombia, Peru, Venezuela, upper Amazon, Rio Negro, Orinoco, Inirida, and Casiquiare. 4-6 cm. Body elongated, laterally compressed, mouth quite large. Males have a head with a massive lower jaw. A black vertical stripe runs along the edge of the upper jaw. Further back, another stripe crosses the head from top to bottom.
The overall body tone of the male is reddish with a soft pearly sheen. The back is reddish-brown. A light yellowish stripe runs along the body, and below it a dark blue stripe with a blurred lower edge. Light blue, bright scales are located on the dark stripe. The belly is pinkish in color. Males have noticeably enlarged dorsal and anal fins, adorned with red flecks. The dorsal is reddish, and its middle part is sprinkled with bluish spots. Each ray of the dorsal fin begins with a white dot. On the caudal fin, red flecks are located on the outer rays.
The female is light brown. She also has both light and dark stripes and shiny scales. There are no black stripes on her snout, and she is 1.5 times smaller. During spawning, the female becomes very dark, with only the anal fin being bright red. Males and females from Colombia and Brazil are more intensely colored than specimens from Venezuela, whose coloration lacks red. Males from Venezuela have shorter fins and exhibit yellow coloration in the head region, including the gill covers.
This is a bottom-dwelling fish, unfortunately very timid, staying in or near a hiding place. Adult males occupy territories on the bottom and attempt to control them, competing with each other. During such ritualistic fights, they flare their gills, spread their magnificent fins, and attack the base of the rival’s caudal fin head-on. They look quite aggressive, but are actually peaceful. During the spawning period, territorial behavior is characteristic of males. Having claimed a territory 20-30 cm in diameter, in the center of which is a secure hiding place (a cave, half a coconut shell, or suitable driftwood), they drive away other males of their own species and other fish.
Poecilocharax swim in the lower part of the aquarium, near the bottom. Unlike many characin fish, they do not form a school; all fish keep to themselves. At the same time, they behave much more strictly towards conspecifics than towards fish of other species, and pay no attention at all to fish in the upper layers. However, introducing them into an aquarium with other species is not recommended — you might simply never see this very timid fish. Females wander more freely among the plants. Natural behavior can only be observed in a separate species-specific aquarium with hiding places. They move in jerks with distinct stops.
The aquarium should be heavily planted, with floating plants on the water surface, and hiding places must be provided. Driftwood, rounded boulders, and floating plants with thread-like roots serve as hiding places. When acquiring Poecilocharax from the trade, it is important to ensure that the fish have a straight belly area; otherwise, the fish typically die even despite good feeding.
The water should be slightly brown in color. A peat filter is mandatory and must be cleaned frequently. For successful maintenance, the fish require very soft water below 5° dH, acidic water with a pH below 6, and water free of nitrates. Often, outwardly healthy animals die a few days after being introduced into the aquarium. They quickly perish in ordinary water. The pH level must be checked regularly to prevent severe fluctuations.
They are not suitable for beginner aquarists. Very difficult to keep. A significant problem is associated with these exceptionally beautiful fish — feeding. They prefer only live foods, including fish fry. Considerable patience will be required to transition them to other foods. Fish are fed enchytraeids, tubifex, and small bloodworms.
Sexual maturity is reached at 8 months; the candidate for spawning is the most handsome dominant male. Narrow tubes that are not too long are preferred for reproduction — 4-5 cm is sufficient. Their diameter is important and should be about 1 cm. The male guards the clutch and fans it with tail movements. He does not feed during all this time. The female may also look after the eggs, but the male chases her away. Not recommended for beginner aquarists. T 24-28°C; pH 5.0-6.5; dH up to 5°.
Identification: Black Darter Tetra — Poecilocharax weitzmani.
Characidium crandellii, fasciatum, rachovi.
Genus Elachocharax, Genus Klausewitzia, Genus Melanocharacidium, Genus Odontocharacidium. 
