Apistogramma nijsseni Kullander, 1979. Revue suisse Zool. 86, p. 938, fig. 1 (Perú (Loreto), R. Ucayali system, Jenaro Herrera, R. Copal, "marigots des Tupacs").
Apistogramma nijsseni, NRM 18078, adult male, 32.6 mm SL, just collected from the wild near Jenaro Herrera, c.15 km on road Jenaro Herrera-Colonia Angamos. 1 September 1981 (SOK 043). Photo © S.O. Kullander.
Apistogramma nijsseni is a moderately deep-bodied species with pronounced sexual dichromatism. Males reach 39.2 mm, and females 30.7 mm SL in the wild. Males may reach 52 mm SL in aquaria, however. Both sexes have short dorsal-fin lappets and clearly rounded caudal fin. There is no evidence of a lateral band at any size, but roundish lateral and caudal spots are well evident. In females the suborbital stripe, lateral spot, and caudal spot are greatly expanded; the suborbital stripe may cover all of the cheek and gill-cover. Living males are blue on the sides. Lateral and caudal spots show only faintly. Dorsal and caudal fins have bright red margins. Living females are yellowish with deep black suborbital stripe, lateral spot and caudal spot. Cephalic lateralis pores as in A. cacatuoides, with 3 infraorbital and 5 dentary pores. Anteroventral half of cheek naked. Simple (anteriorly) and bicuspid (posteriorly) lower pharyngeal teeth. Counts: D. XV.7-8, XVI.6-7, XVII.6, usually XVI.7; A. III.6-7, usually III.7; E1 row scales 22 (rarely 23) ; cheek scale series 2-4; gill-rakers 1-2 (de Rham & Kullander, 1983; Kullander, 1986).
Apistogramma nijsseni, generalised colour pattern of females in the type series. Note large dark blotches, not present in the male. Drawing S.O. Kullander.
The original description (Kullander, 1979) was based on females only, showing characteristic black blotches on the sides of the head, midbody and caudal fin base. Males were first reported by de Rham & Kullander (1983).
MHNG 1595.82. Adult female, 30.7 mm SL. Perú (Loreto), R. Ucayali system, Jenaro Herrera, R. Copal, "marigots des Tupacs". 18 October 1977. P. de Rham.
nijsseni, for Han Nijssen, ichthyologist, Curator of Fishes in the Zoölogisch Museum, University of Amsterdam.
Restricted to the Quebrada Carahuayte, a left bank tributary of the Ucayali River in Peru. It is known only from small streams (quebraditas) along the road from Jenaro Herrera towards Colonia Angamos, starting at the km 13 mark and extending to the Quebrada Carahuayte.
The natural habitats were described and discussed at length by de Rham & Kullander (1983). The species occurs in small, shaded streams with clear, tea-brown water. Recorded water data are: pH 5.0-5.6, hardness less than 1 °dGH, temperatures 24.5-27.5 °C, conductivity 3-14 μS. Oxygen readings gave 02 saturation 39% (after rain) in one site, 79.5% in another site. Associated species occasionally included the congeneric species A. agassizii or A. eunotus
KULLANDER, S.O. 1979. Description of a new species of Apistogramma from Peru. Revue suisse de Zoologie, 86: 937-945.
KULLANDER, S.O. 1986. Cichlid fishes of the Amazon River drainage of Peru. Swedish Museum of Natural History, Stockholm, 431pp.
de RHAM, P. & S.O. KULLANDER. 1983. Apistogramma nijsseni Kullander un nouveau Cichlidé nain pour l'aquarium. Revue française d'Aquariologie, 9: 97-104.