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his month, we are concentrating on the Heptapteridae family and the Brachyrhamdia genus, namely Brachyrhamdia rambarrani. This species is not seen as much in the hobby as B. imitator and, as such, is quite rare. The common name of 'False Adolfoi' is due to its habit of schooling with this species of Corydoras (Hoplisoma adolfoi) and is sometimes found as contaminents in exports of Hoplisoma adolfoi.

    Brachyrhamdia rambarrani

There is a scenario that states that the Brachyrhamdia are practising a Batesian form of shoaling, whereas they take food that the Corydoras dig up from the substrate, and also steal the eggs of these species. They seem to do better with Corydoras (Hoplisoma) that possess a black eye stripe and the orange head blotch, such as H. davidsandsi, H. adolfoi, H. melini, and other species from the upper Rio Negro rather than plain species such as Osteogaster (Corydoras) aenea, which tend to be nipped and driven out of the shoal.

In other reports, the thinking is that it is a form of Müllerian mimicry. Müllerian mimicry is a phenomenon in which two or more species with effective defences share a similar appearance, such as bright colouration or patterns. This shared warning signal is a mutualistic relationship because it reduces the number of individuals from each species that must be sampled by predators before they learn to avoid them. This hypothesis stems from the fact that the body of the Brachyrhamdia species has no body armour, whereas the Hoplisoma (mentioned above) species possesses body armour.

False Adolfoi

Pimelodella rambarrani

Rhamdiinae

South America: Unini River basin in upper Negro River drainage, Brazil. Type locality: Reportedly from the Rio Unini, a tributary of the Rio Negro, Amazonas, Brazil.

7.0cm. (2¾ins)

24-26°C (75-79°F)

Short and compact body. Posterier cranial fontanelle wide open from the frontals to the supraoccipital.

House in aquaria (24ins/60cm or over) with alternate sand and gravel substrate. Provide planted area. Keep in a species tank or with Corydoras (Hoplisoma) and larger Characins or Anabantoides in the top half as they can be predatory with small species such as Neon Tetras. Provide plenty of water changes and a good filtration system.

Spawns amongst plants especially Vallisneria with B. imitator with Corydoras (Hoplisoma melanistium) melanistius as tankmates. There is an article on the website of the spawning of a close relative, Brachyrhamdia imitator. Article here.

Males have an elongated genital papilla and females are bulkier in the body.

Tablet and pellet foods. Frozen and live foods such as bloodworm. Insect larvae. Not a fussy eater.

Fontanelle: The space(s) between the bones on top of the skull covered by skin.
Genital papilla: A small, fleshy tube behind the anus in some fishes, from which the sperm or eggs are released; the sex of a fish often can be determined by the shape of its papilla.
Supraoccipital: Unpaired bone at the back of the skull, usually with a crest.

Brachyrhamdia: Brachy = short; rhamdia = from the vernucular name 'Nhamdia or 'Jamdia.
rambarrani: In honour of Harry Rambarran (1935–2022), then co-manager of International Fisheries, Inc. (Hialeah, Florida, USA), an aquarium-fish exporter that supplied holotype.

Photo Credits

©  Johnny Jensen @  
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