Taxonomy & naming
Boehlkea fredcochui was described by the French–Brazilian ichthyologist Jacques Géry in 1966. It is placed in the monotypic genus Boehlkea, which Géry erected to accommodate it; no other species have been assigned to the genus. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) records the valid name as Boehlkea fredcochui Géry, 1966. The genus belongs to the family Characidae — a vast and taxonomically complex assemblage — and has historically been associated with the tribe Stevardiidae, though higher-level classification within Characidae continues to be revised as phylogenetic work accumulates.
The species epithet honours Fred Cochu, a well-known aquarium-fish exporter and importer who played a significant role in introducing Amazonian species to the hobby trade during the mid-twentieth century; the common name Cochu's blue tetra directly reflects this patronym. The generic name Boehlkea commemorates the American ichthyologist James E. Böhlke (1930–1982), a specialist in Neotropical characids whose work at the Academy of Natural Sciences of Philadelphia substantially advanced knowledge of the family.
Morphology
Boehlkea fredcochui is a small, slender-bodied tetra reaching a maximum total length of approximately 2 in, with most aquarium specimens remaining somewhat smaller. The body plan is the classic characid form: moderately compressed laterally, with a complete lateral line, a small adipose fin between the dorsal and caudal fins, and a forked caudal fin.
The colour pattern is the species' defining character. The head and anterior portion of the body carry a vivid blue to blue-green iridescence — a structural colour that shifts with angle of light — while the caudal fin and the caudal peduncle region are distinctly reddish to orange-red, giving the fish a bicolour appearance somewhat reminiscent of neon or cardinal tetras, though Boehlkea is not closely related to those species. A dark horizontal stripe runs along the midline, contributing to the overall two-tone effect. Females tend to be slightly deeper in the body and, particularly when in breeding condition, somewhat plumper in the abdomen; males are generally slimmer.
Habitat
Boehlkea fredcochui is native to Peru, where it is recorded from tributaries of the upper Amazon basin including the río Napo drainage and associated waters such as the río Copataza and río Arajuno drainage. These rivers drain the Andean foothills and adjacent lowland forest, producing water that is typically clear, soft, and acidic — a characteristic blackwater or clearwater environment with low conductivity and pH values well below neutral.
The species inhabits clear, acidic streams and tributaries where it schools in open water and along vegetated margins. Water temperatures in these Peruvian Amazonian drainages are tropical, with sources reporting a range of roughly 72–82 °F (72–82 °F) across the literature, and pH values generally acidic to near-neutral, most references citing around 6.0–7.0 as typical. These parameters are consistent with the soft, low-mineral streams of the upper Amazon piedmont.
Feeding
In nature, Boehlkea fredcochui feeds as an opportunistic micropredator in the manner typical of small Amazonian characids, consuming small insects and their larvae, tiny crustaceans, and other invertebrates, as well as algae and fine plant or organic matter. Its small mouth is suited to correspondingly small prey items, and the species forages actively in the water column.
In the aquarium it accepts a wide range of commercially available foods without difficulty: quality small-particle flake, micro-pellets, and frozen or live foods such as Daphnia, baby brine shrimp, micro-worms, and finely chopped tubifex. Supplementing the staple diet with varied live and frozen invertebrate foods improves colour intensity and helps condition fish for breeding. The species is peaceful at feeding time and not competitive enough to exclude slower tankmates from food, though it should not be kept with fish large enough to view it as a meal.
Mating
Boehlkea fredcochui is a typical egg-scattering characid: spawning is open, non-territorial, and involves no pair bond or parental investment. Under good conditions mature fish will spawn readily, with males actively pursuing females and driving them toward areas of fine-leaved vegetation or substrate where eggs are deposited. No courtship display comparable to the elaborate visual signalling of cichlids has been described; breeding is more an energetic chase than a structured ritual.
Eggs are small and, according to hobbyist reports, amber-coloured. They are scattered among fine-leaved plants or deposited in vegetation mats where they adhere briefly before settling. Like virtually all egg-scattering tetras, adults show no recognition of or interest in their own eggs — they will consume them immediately if given access — so removing adults promptly after observed spawning, or moving egg-laden plants to a separate vessel, is standard practice.
Breeding
Successful breeding of Boehlkea fredcochui in captivity follows the same general approach used for other small Amazonian egg-scattering tetras. Conditioning a group of well-fed adults on varied live and frozen foods for a week or two brings females into spawning condition and stimulates male activity. A separate, dimly lit breeding tank with very soft, acidic water — pH around 6.0, low hardness, temperature approximately 75 °F (75 °F) — and clumps of fine-leaved plants such as Java moss, Cabomba, or synthetic spawning mops provides the setup that triggers spawning.
Eggs hatch at around 75 °F in approximately three days. The newly hatched larvae initially absorb their yolk sacs and are largely immobile before becoming free-swimming. First foods must be very fine: infusoria, commercially available liquid fry foods, or rotifers are appropriate starters, followed by freshly hatched brine shrimp nauplii as the fry grow. The fry are small and require clean, well-oxygenated water with gentle filtration — a sponge filter is ideal to avoid losses from intake suction. Growth is moderate; juveniles begin to show adult colouration within a few weeks.
In the aquarium
Cochu's blue tetra is a peaceful, active schooling fish best displayed and maintained in groups of eight or more; smaller groups tend to produce shy, stressed fish that remain in cover and show little colour. The iridescent blue is at its most vivid under good lighting and against a dark substrate, and the fish show best when kept in a planted aquarium with open swimming space and a dark or natural background. A tank of 23.5–29.5 in or more in length suits a small school comfortably.
Water conditions should mirror the species' soft, acidic Peruvian origins: pH 6.0–7.0, hardness ideally below 10 dH, and temperature in the range of 72–82 °F (72–82 °F). The species is reportedly tolerant of a broader pH range up to around 8 in harder water — hobbyist sources list up to pH 8 as workable — but it colours up and conditions best in the soft, slightly acidic water it comes from. Tankmates should be similarly sized, peaceful species that occupy complementary water zones; other small characids, small rasboras, corydoras catfish, and dwarf cichlids are natural companions. Lifespan in good conditions is typically four to five years. Despite its striking appearance, Cochu's blue tetra remains less commonly seen in the hobby than the most popular tetras, making it a rewarding find for aquarists seeking something beyond the familiar neons and cardinals.
Conservation
Boehlkea fredcochui is assessed as Least Concern (LC) on the IUCN Red List, with the most recent assessment dated October 2022. The species occupies Peruvian Amazon drainages that remain relatively intact compared to heavily deforested regions further south and east, and there is no current evidence of significant population-level decline. Its collection for the ornamental fish trade has a long history — it was among the Amazonian tetras introduced to the hobby by mid-twentieth-century exporters — but trade pressure alone has not driven documented declines in wild stocks.
The broader context for any Amazonian fish includes ongoing threats from deforestation, agricultural runoff, and infrastructure development across the Peruvian upper Amazon piedmont. The species' dependence on clear, acidic, soft water makes it potentially sensitive to catchment changes that alter water chemistry or turbidity. For aquarists, captive-bred stock — increasingly available from specialist breeders — represents the most straightforward way to support the species without contributing to wild collection pressure, while also ensuring fish acclimated to aquarium conditions.