#1018 Igarapé do Daracuá – Shallow Blackwater Habitat of the Middle Rio Negro

Biotope Information

This aquarium recreates a shallow blackwater habitat of the Igarapé do Daracuá, near Barcelos, in the middle Rio Negro region of Amazonas, Brazil. The habitat represents a small forest stream flowing through seasonally flooded Amazonian forest. The underwater environment is characterized by fine pale sand, submerged roots, fallen branches, twigs and leaf litter. The water is naturally stained dark amber to tea-brown by tannins and humic substances released by decomposing leaves and wood. The habitat is soft, acidic and very low in dissolved minerals, with slow-moving water and seasonal changes in water level. The aquarium intentionally follows a classic Amazonian blackwater biotope approach, without artificial CO₂ or fertilization. Only small, carefully placed patches of Eleocharis sp. are used as subtle details to enhance naturalness, while the dominant visual elements remain the sand, roots, branches, leaf litter and tannin-stained water. Paracheirodon axelrodi (Cardinal Tetra) is the only fish species kept in the aquarium. The schooling behavior and intense blue and red coloration of the Cardinal Tetra contrast naturally with the dark water and shaded environment, reproducing a characteristic visual feature of the Rio Negro blackwater habitat. The composition was designed to recreate the shallow margins of the flooded forest, where fish move among submerged roots and branches beneath filtered sunlight. The aquarium aims to reproduce not only the visual appearance, but also the ecological character of this Amazonian blackwater environment. References used for accuracy include published descriptions and scientific literature on the Igarapé do Daracuá and Middle Rio Negro blackwater habitats, including Amazonas Magazine.