Maximum size : 3 cm

Eilyos Tetra - Hyphessobrycon eilyos : Complete Fish Profile & Care Guide

Table of contents


Eilyos Tetras (Hyphessobrycon eilyos) are peaceful and undemanding species renowned for their adaptability to various conditions. While these remarkable fish can acclimate to different environments, it is important to note that very hard water may hinder their full potential, particularly when it comes to showcasing their vibrant colours. To unlock their true magnificence, consider creating a planted aquarium adorned with darker substrates and subdued areas, providing an ideal home that enhances their colours and promotes their overall well-being.

While Eilyos Tetras exhibit a peaceful nature, it is essential to be mindful of their interactions with long-finned species such as guppies or Siamese Fighting Fish, as they may display occasional fin-nipping tendencies, particularly if kept in smaller numbers. To foster a harmonious community, it is recommended to maintain Eilyos Tetras in a group of eight or more individuals. This not only ensures their optimal welfare but also creates a visually captivating and natural-looking shoal, offering a sense of security to these beautiful fish. Within such groups, prepare to witness stunning displays of fin flaring as rival males vie for dominance, adding a dynamic touch to your aquatic landscape.

When selecting tankmates for your Eilyos Tetras, consider companions that complement their peaceful nature. Species such as Corydoras Catfish, Hatchetfish, Loaches, Rasboras, small to medium-sized Barbs, Gouramis, and West African Dwarf Cichlids make ideal companions, fostering a harmonious coexistence within the aquarium. Additionally, due to their distinctive shape, Eilyos Tetras can also thrive alongside larger Cichlids such as Discus and Angelfish. However, please exercise caution and ensure that they are not housed with significantly larger, boisterous species, as Eilyos Tetras may quickly become startled or intimidated.

Distinguishable by their unique features, Eilyos Tetras can be identified by the absence of humeral and caudal spots, as well as the presence of numerous dark chromatophores on the lateral surface of their bodies. In addition, the vibrant hues of their pelvic, caudal, adipose, and caudal fins captivate the eye, while possessing 7 to 11 maxillary teeth adds to their remarkable attributes.

Embrace the allure of Eilyos Tetras as they grace your aquatic landscape with their tranquil presence, inspiring a sense of awe and wonder. Create a harmonious environment that celebrates their peaceful nature and showcases their remarkable colours, cultivating an enchanting underwater realm that mesmerizes both enthusiasts and casual observers alike.

Eilyos Tetra Photos

Sexual Dimorphism

Distinguishing between male and female Eilyos Tetras is a straightforward task. As these captivating fish mature, males exhibit notable characteristics such as extended anal and dorsal fins, showcasing a more significant, sleeker physique and a more vibrant colouration compared to their female counterparts.

Quick Facts

Scientific NameHyphessobrycon eilyos
Year Described2003
Other NamesNone
Max Size3 cm
Aquarium LevelMiddle - Top
DifficultyBeginner - Intermediate
Best kept asGroups 8+
Diet & FeedingOmnivore
LifespanUp to 5 Years

Water Parameters

Water TypeFreshwater
pH 5.5 - 7.5
GH 1 - 12
Ideal Temperature
75 - 82
23 - 28

Natural Habitat

Eilyos Tetras claim their realm in the upper Rio Araguaia Basin, a beautiful region nestled within the heart of Brazil, South America. These remarkable Tetras thrive in these pristine waters, characterized by their clarity and gentle currents. Delicate yet resilient, they navigate the enchanting depths of small and shallow waterways, where a tapestry of colours emerges from the interplay of sunlight and the release of tannins and other organic compounds, painting the water with a rich, amber hue.

Venturing deeper into their habitat, one discovers a captivating sight—the sandy substrate, a soft bed that anchors the aquatic landscape. Here, Eilyos Tetras gather, forming small patches of vitality amidst the gentle flow. Among these clusters, the Tetras find solace and camaraderie, seeking refuge in the embrace of aquatic vegetation and the shelter provided by submerged wood—elegant roots and fallen branches that grace the water with their presence.

Witness the mesmerizing world of Eilyos Tetras as they harmonize with their surroundings, an intricate dance within a realm of natural beauty. From the sandy substrate to the vibrant pockets of aquatic life, this remarkable species epitomizes the captivating allure of the upper Rio Araguaia basin, a testament to the mesmerizing wonders that await within the depths of Brazil's South American treasure.

 Araguaia River - Brazil
Brazil Flag


Regrettably, comprehensive information on Eilyos Tetras remains scarce; however, we can infer potential breeding methods based on our understanding of similar Hyphessobrycon species. Establishing a dedicated breeding tank is crucial to successfully breeding Eilyos Tetras and optimising fry production. This specialised environment should feature subdued lighting and provide suitable structures like bundles of fine-leaved plants such as java moss, which serve as ideal locations for egg deposition. Alternatively, the tank bottom can be covered with mesh, allowing the eggs to drop through while keeping the adults at bay. Maintaining soft and acidic water conditions, with a pH range of 5.5 to 6.5, water hardness between 1 and 5, and a temperature maintained at 80 to 84 degrees Fahrenheit, is imperative. Employing peat filtration and utilising reverse osmosis (RO) water can also prove beneficial in maintaining optimal conditions. A gentle current can be achieved by using a small air-powered sponge filter.

Breeding Eilyos Tetras can be accomplished either in a group setting, with an ideal ratio of half a dozen individuals of each sex, or through pair spawning, conditioning female and male groups separately in dedicated tanks. When females exhibit a noticeable fullness of eggs and males display their most vibrant colours, select the plump female and best-coloured male, transferring them into the spawning tank in the evening. The spawning ritual typically unfolds the following morning. Swift separation is necessary to safeguard the precious eggs, as adults may consume them if given an opportunity. Generally, eggs will hatch within 24 to 36 hours, and around five days later, the fry will embark on its free-swimming phase. Initially, nourishing the fry with infusoria-based food is recommended until they reach a suitable size to consume brine shrimp nauplii, microworms, and crushed flake food. Given the sensitivity of eggs and fry to light during their early stages, it is advisable to maintain a darkened environment whenever feasible.

Unlock the mysteries of Eilyos Tetra breeding, navigating the limited information available to create a nurturing haven where new life flourishes. With meticulous attention to breeding tank setup, water parameters, and proper feeding techniques, you can unlock the secrets of successful Eilyos Tetra reproduction, delving into the remarkable journey of life from inception to the emergence of vibrant fry.

Diet & feeding

Eilyos Tetras exhibit a versatile appetite, readily accepting a diverse range of foods. However, to ensure their optimal health and well-being, providing them with a well-rounded and varied diet is recommended. This can be achieved by incorporating high-quality dried foods, including micropellets, flakes, and granules, into their feeding regimen. Additionally, supplementing their diet with live and frozen options such as vitamin-enriched brine shrimp, bloodworms, white mosquito larvae, daphnia, and brine shrimp will enhance their nutritional intake.

When it comes to feeding frequency, offering meals once or twice a day is sufficient. It is essential to provide an amount that can be consumed within a timeframe of approximately three minutes or less. By adhering to this feeding practice, you ensure that your Eilyos Tetras receive an appropriate quantity of nourishment while preventing overfeeding and maintaining optimal water quality within the aquarium.

Other Tetras of interest