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Garold W. Sneegass (1)

Habitat: They inhabit underground habitats both north and south of the mouth of the Amazon River as well as the Marajó Island. This fish inhabits superficial, phreatic habitats, but does not live in the deeper artesian aquifers. The head of this species is distinctly wider than the body. The integument is thick and opaque. The lateral line is reduced and the pelvic fin is highly variable in length between specimens, and can be reduced to finger-like projections. P. cisternarum hide and fit tightly within crevices of rocks, where they stay most of the time, leaving only for food. These fish are not a burrowing species, nor do they hide under vegetative matter, restricting themselves to these crevices. They do not interact much with each other and do not seem to be gregarious. Colouration: The red colouration is generally uniform over the body and head and is due to superficial blood; this red coloration does not extend to the fins. The fish is darker on the dorsal surface due to some pigmentation in the skin. The barbels are whitish and fade to transparent tips. Reproduction: Nothing is known about the reproductive habits of this species. Diet: They feed on macro-invertebrates such as worms. They either swallow their prey whole, or take a bite out of it, rolling their body, and twisting a piece off. This firm grip is due to extremely large jaw muscles, which are well adapted to feeding on relatively large prey; worms eaten in captivity can be as long as the fish itself. It is unknown what invertebrates P. cisternarum actually feeds on in its natural habitat. Becauses food is rare in their environment, these fish are able to last up to a year without feeding, which is partially because of their inactivity. Remarks: These fish indicate they have some form of respiration that allows them to breathe air, however this behavior is only exhibited under stressful conditions. It is supposed that these fish also have a form of cutaneous respiration, as they are small, live in conditions with low dissolved oxygen, and have high blood circulation to their skin (which provides its red colouration).

None

Heptaterus cisternarum

Phreatobiidae

South America: Phreatic environments. Brazil: Pará and Amapá states: at the Rio Amazonas delta; Belém city, Pará, and Macapá city. Original locality: Marajo I., at the mouth of the Amazon, Brazil

5.5cm. (2¼ins)

23-25°C (73-77°F)

6.5-7.5.

Muriel-Cunha, Janice; de Pinna, Mário (2005). "New data on Cistern Catfish, Phreatobius cisternarum, from subterranean waters at the mouth of the Amazon River (Siluriformes, Incertae Sedis)" Papéis Avulsos de Zoologia (Museu de Zoologia da Universidade de São Paulo) 35: 327. ISSN 1807-0205.