Taxonomy & naming
Tyttocharax cochui was described by the German ichthyologist Werner Ladiges in 1950. The authority appears in parentheses because Ladiges placed the species in a different genus at the time of description, and a subsequent revision transferred it to Tyttocharax, necessitating the parenthetical notation under ICZN rules. Eschmeyer's Catalog of Fishes (Catalog of Fishes, California Academy of Sciences) serves as the authority for the valid name and placement.
The genus Tyttocharax belongs to the large and heterogeneous family Characidae — the characins — and is characterized by its extremely small body size relative to most of its relatives. The systematics of small Amazonian and trans-Andean characins remain a work in progress, and Tyttocharax occupies a corner of the tree where morphological characters distinguishing genera can be subtle. The specific epithet cochui honours a person named Cochu; beyond that the dedicatory context is not documented in sources available for this article.
Morphology
Tyttocharax cochui is a very small fish, reaching a maximum standard length of approximately 1 in — placing it firmly among the nanoscale characins. The body form follows the typical small-tetra pattern: laterally compressed, roughly fusiform, with a forked caudal fin and the small adipose fin characteristic of most characids. Eyes are proportionally large relative to head size, as is common in diminutive fishes.
Published coloration data for this species is sparse. As a small pelagic freshwater characin from Peruvian Amazonia it is likely silvery to translucent, possibly with a faint lateral stripe or caudal spot, but specific pigmentation details are not well documented in the literature accessible for this article. The trophic level recorded in FishBase (3.0) is consistent with a small invertivore feeding on zooplankton and microinvertebrates.
Habitat
Tyttocharax cochui is a freshwater species recorded from Peru, placing it within the Amazon basin or associated Peruvian drainages. FishBase classifies it as pelagic and tropical, indicating a preference for open water in the mid-column rather than a bottom-associated lifestyle.
Detailed habitat data for this species — river system, substrate type, water chemistry at collection localities — are not well documented in the sources available for this article. As a small Amazonian characin, it most likely inhabits slow-moving to still waters with blackwater or clearwater characteristics typical of the Peruvian Amazon lowlands, but this should be regarded as inference from the broader ecological context of similar species rather than confirmed observation.
Feeding
With a FishBase trophic level of 3.0, Tyttocharax cochui sits at the lower end of the carnivore range, consistent with a diet of small zooplankton, microcrustaceans, and larval invertebrates. This is the typical feeding guild of very small characins operating in the pelagic zone of Amazonian waters.
In an aquarium setting, a fish of this size would likely accept commercially available micro-foods: finely powdered dry foods, live or frozen cyclops, newly hatched brine shrimp nauplii, and similar micro-prey. Because the mouth gape at 1 in SL is extremely small, appropriately sized particles are essential.
Mating
No specific reproductive observations for Tyttocharax cochui are available in the published literature or hobbyist literature consulted for this article. As a member of the family Characidae, the default reproductive mode is egg-scattering with no parental care — adults broadcast adhesive or semi-adhesive eggs among fine-leaved aquatic vegetation or over substrate, then abandon them.
Small characins of similar ecology typically spawn in loose pairs or small groups triggered by water temperature changes, soft slightly acidic water, and the presence of fine plant material. Eggs hatch within one to three days at tropical temperatures, and fry require very small first foods given the diminutive adult size. Whether Tyttocharax cochui deviates from this general pattern is not documented.
Breeding
Captive breeding records for Tyttocharax cochui are not documented in the sources available for this article. If the species follows the typical small-characin pattern, a breeding setup would include soft, slightly acidic water, fine-leaved plants or a synthetic spawning mop, subdued lighting, and the removal of adults after spawning to protect the eggs.
At 1 in maximum size, the fry would be exceptionally small at hatching, requiring infusoria or commercial liquid fry food as first foods before transitioning to nauplii. The scarcity of hobbyist records probably reflects limited availability of the species in the trade rather than any particular breeding difficulty.
In the aquarium
Tyttocharax cochui is a rare fish in the aquarium hobby, and very little husbandry documentation exists for it. Its maximum size of 1 in makes it suitable only for nano aquaria or for specialist setups dedicated to micro-fish; it would be overwhelmed or outcompeted in any community tank with standard-sized tetras or other similarly scaled species.
As a pelagic species it would benefit from open water in the mid-column, a well-planted perimeter providing cover, and dim to moderate lighting. Water parameters consistent with Peruvian Amazonian conditions — soft, slightly acidic to neutral, and warm (roughly 73–82 °F) — are a reasonable starting point in the absence of specific habitat data. Given its rarity, the species is primarily of interest to specialists in small characins and those maintaining Peruvian biotope aquaria.
Conservation
Tyttocharax cochui is assessed as Least Concern (LC) on the IUCN Red List. The LC designation indicates that the species does not currently meet the thresholds for a threatened category based on available data, and no major population-level declines have been documented.
As a small, poorly known Amazonian characin, the species benefits from the general relative intactness of large areas of Peruvian Amazonian habitat, though deforestation and water-quality changes driven by agriculture and resource extraction remain ongoing pressures across the region. Continued monitoring of small-bodied, potentially range-restricted species like this one is warranted as Amazonian habitats face increasing pressure.