Nannocharax signifer was found in the Ouémé basin, Benin, West Africa.
Distribution map of Nannocharax signifer in Benin West Africa.1 = Hlan River, 2 = Zou River at Cové, 3 = Ouémé River at Bétérou.
So far Nannocharax signifer is only known from 3 localities in the Ouémé basin,
- Hlan River close to Zogbodome
- Zou River at Cové
- Ouémé River at Bétérou
These two localities differ much from each other
- a narrow stream (± 3m width)
- dense vegetation on its banks
- The Hlan River is a real forest stream, never receiving direct sun light and with a bottom substrate of mud, sand, leaves, roots and drift wood. Its shores are steep and overhanging and N. signifer was collected
between the roots of the overhanging bank.
- This small river flows into the Lokoli swamp forest before continuing in more open areas, draining into the Ouémé Lagoon, Lake Nokoué, but also having direct connections to the Ouémé River via short-cuts.
- a larger stream (± 15m width)
- sparse vegetation in the form of small bushes and solitary trees
- The Zou River in the Cové area is wide
- shores are overgrown mainly by Mimosa shrubs
- provide little shady areas
- substrate consists mainly of sand and gravel.
8 of the other 28 Nannocharax species are from West Africa, west and north of and including the Cross river:
- Nannocharax ansorgii
- Nannocharax fasciatus
- Nannocharax latifasciatus
- Nannocharax lineomaculatus
- Nannocharax occidentalis
- Nannocharax reidi
- Nannocharax usongo
- Nannocharax zebra