Retroculus lapidifer

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Matt Clarke manages to track down some rare Retroculus lapidifer at a shop in Northampton.

Scientific name: Retroculus lapidifer

Origin: Rio Tocatins, Capim and Amazonas drainages.

Size: Up to 20cm/8".

Habitat: Retroculus are adapted for life in rapids.

Water: Well-oxygenated, soft, acidic water.

Diet: The protrusible lips resemble those of the African Gnathochromis permaxillaris, and the fish appear to feed in a similar manner by sucking insect larvae out of the substrate. Aquarium specimens will accept most foods.

Aquarium: Fast-flowing water and smooth, water-worn pebbles and boulders are ideal. Can sometimes be quite territorial, but generally leaves non-territorial species well alone.

Sexing: Difficult to sex,

but males are usually bigger and have dorsal and anal fin extensions. The lips of males may be thicker.

Breeding: They are said to be substrate spawners and lay their eggs on a flat pebble. They may move this spawning site around the tank. The latin lapidifer means 'stone-mover'.

Similar species: Two other species, besides lapidifer, have been formally described. R. xinguensis and R. septentrionalis were both described by Gosse.R. xinguensis is from the Arapiuns, Xingu, Tocatins and Amazonas drainages, while septentrionalis is found in the Oyapock and Araguari drainages. There are several variants of lapidifer, with a colourful form found in the Tocatins which has more red on it and bluer lips.

Identification: The easiest way to spot lapidifer is by a process of elimination, since it lacks the vertical stripes of the caudal fin present in the others. R. lapidifer also has 36-39 scales in the lateral series, 15-17 dorsal spines, 10-11 branched dorsal rays. R. septentrionalis has less scales in the lateral series (34-37), 14-15 dorsal spines and 10-11 branched rays, while R. xinguensis has 16-17 dorsal spines, 10-12 branched dorsal rays and 37-41 lateral series scales.

Notes: DNA studies have shown them to be basal in the phylogeny of Neotropical cichlids.

Availability: Rather rare. These were on sale at Maidenhead Aquatics in Harlestone Heath, which imported them from Brazil.

Price: On sale for 25.