Matt Clarke looks at the very rarely seen Rio Negro dwarf cichlid, Nannacara adoketa.
Scientific name: Nannacara adoketa
Origin: This species comes from the blackwaters of the middle Rio Negro in Brazil.
Size: Not known, but males probably reach about 5cm/2"; females smaller.
Water: The Rio Negro is a blackwater river with a pH of 3.5-5.0 and extremely soft.
Diet: Not known, but probably detritus, insect larvae and the like. Try flakes, granules and frozen foods.
Aquarium: Prada-Pedreros says that the fish is found in shallow (less than 30cm/12" deep) streams in forest that floods when the main river rises (inundable forest). I'd go for a silver sand substrate along with plenty of bits of bogwood and perhaps some beech tree leaves. I saw no plants in the Rio Negro forest streams I visited. These streams are rich in Apistogramma, lebiasinids and small characins, so these would make good tankmates. Use soft, RO-based water if you want the fish to breed.
Adult colouration: This male wasn't looking his best when the picture was taken in the photo tank. In breeding dress, before we moved him, the male had lots of blue-green spangling on the chest, belly and pelvics, and a number of dark uneven bars and blotches on the head and flanks. Females are, however, relatively plain with a black boomerang-shaped bar through the eye.
Notes: This stunning dwarf cichlid was described in 1993 by Sven Kullander Saul Prada-Pedreros. The name adoketa roughly translates to "unexpecte" and refers to the collection locality in the Rio Negro. Most other Nannacara occur in rivers nearer the coast. Some experts think that this fish and bimaculatum might actually be members of a different genus, rather than true Nannacara.
Similar species: There are now five species in the genus: N. adoketa, N. anomala, N. aureocephalus, N. bimaculata and a new one, described in December 2004, called N. quadrispinae.
Availability: These are extremely hard to get hold of. Tom Halvorsen Ltd (0797 709 8127; www.tomhalvorsen. co.uk) currently just has this single male fish left.
Price: Up to about 100 for a good pair.
Matt Clarke