Taxonomy
Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Lebiasinidae subfamily: Pyrrhulininae
Genus: Nannostomus
mortenthaleri, Nannostomus marginatus Paepke & Arendt 2001:144, Figs. 1-6, 10-13, 15 [Verh. Ges. Ichthyol. 2001; ref. 26010]. Small trib. of Rio Nanay at the village of Alvarenga, Loreto, Prov. of Maynas (=Iquitos), 74°25'40"W, 3°31'10"S, Peru. Holotype: MUSM 17719. Paratypes: MUSM 17720 (3); MTD F 24773 (3); ZMB 33228 (4), 33229 (6, stained and partially damaged). Type catalog: Zarske 2003:19 [ref. 27474]. .Synonym of Nannostomus marginatus Eigenmann 1909, but a valid subspecies as described -- (Paepke & Arendt 2001:143 [ref. 26010]). .Valid as Nannostomus mortenthaleri Paepke & Arendt 2001 -- (Weitzman & Weitzman in Reis et al. 2003:245 [ref. 27061]). = Nannostomus mortenthaleri Paepke & Arendt 2001. Lebiasinidae: Pyrrhulininae. Distribution: Nany R. near Albarenga and apparently Tigre R. near Santa Elena in Loreto Dept., Peru.
Nannostomus mortenthaleri (Weitzman & Weitzman 2002)
Description
The fish reaches a length of about 4 cm and only adult males show the deeply red coloration. The sexes are easily distinguished even among juveniles. Males display a white-color pigmentation at the anterior base of the dorsal fin.
Synonyms
Nannostomus marginatus mortenthaleri
Coral Red Pencilfish
Nannostomus cf. marginatus "Red pencil I"
Characidae sp Arc Red Pencil
Red Arc Pencilfish
Peruvian Red Pencilfish
Purpur-Ziersalmler
Ruby Red Pensilfish
Distribution and habitat
Small tributary of Rio Nanay at the village of Alvarenga, Loreto, Prov. of Maynas (=Iquitos), 74°25'40"W, 3°31'10"S, Peru. Also apparently Rio Tigre near Santa Elena in Loreto Dept., Peru.
Discovery
In the Spring of 2000, the fish was discovered in a collection from the middle to upper Rio Nanay near the town of Alvarenga, Peru, by Aquarium Rio Momon, a wild fish export company owned by Austrian collector Martin Mortenthaler. The fish were not particularly common, and only a few hundred were initially collected and exported overseas.
My Experience
They seem to love newly hatched artemia (BBS), but eat most of the food I offer. Brine shrimps (frozen), mosquito-larves (both white, red and black ones), discus-bits and other dry food ; no problem.
In my tanks, they live in tanks with pH from 4,2 - 6,5. I see no difference in behavior as the pH varies, except that fry only grow up in the tank where the pH is below 5,5. Others have breed them in pH 6,5.
They are perfect dithers to dwarf cichlids; they don't bother the cichlids, and the cichlids don't bother them.
Breeding
In my tanks they live among floating plants (Ceratopteris cornuta) in tanks where Apistogramma rules in the lower levels of the tank.
Where they share a tank with Apistogramma elizabethae, the water is pre-filtered through peat, very soft, and with a pH of 4,2 - 5,5.
Here they breed, and a few of the fry grow up now and then.