Cyanogaster noctivaga

Cyanogaster noctivaga
Conservation status
Least Concern  (IUCN 3.1) [1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Characiformes
Family:	Characidae
Genus:	Cyanogaster
Species:	C. noctivaga
Binomial name
Cyanogaster noctivaga Mattox, Britz, Toledo-Piza & Marinho, 2013

Cyanogaster noctivaga is a species of characin native to the Rio Negro, Brazil. ^[2] Its scientific name translates as the blue-bellied night wanderer, referring to its unique appearance and nocturnal habits. ^[3] It was first described in 2013, having been discovered in October 2011 on a scientific expedition organised by the University of São Paulo, Brazil. ^[4]

Description

When alive, Cyanogaster noctivaga is a transparent fish with a blue belly and reddish gill covers, but it quickly loses its bright colours after death. Its eyes are large, and the shape of its snout and its dentition differs from other characins, marking it out as a new genus. The longest specimen found was 17.4 mm (0.69 in) long. ^[3] It differs from other members of the subfamily Stevardiinae in having 8 dorsal-fin rays and four teeth in the inner premaxillary tooth series and i+5 pelvic-fin rays and the presence of a single conical tooth in the outer premaxillary tooth series. There are hooks on the rays of the pelvic and anal fins in mature males. ^[4]

Distribution and habitat

This fish is only known from a single location in the Rio Negro, but as it is a very small fish and seems to be entirely nocturnal, it is easily overlooked. It was found in an acidic backwater, a similar habitat to that of the smallest known species of fish, Paedocypris progenetica , which occurs in peaty forest swamps and blackwater streams in Asia. ^{[3] [5]}

References

1. Lima, F. (2023). "Cyanogaster noctivaga". IUCN Red List of Threatened Species . 2023: e.T164540892A164540907. doi: 10.2305/IUCN.UK.2023-1.RLTS.T164540892A164540907.en . Retrieved 26 April 2025.
2. Thomaz AT, Arcila D, Ortí G, Malabarba LR (2015). "Molecular phylogeny of the subfamily Stevardiinae Gill, 1858 (Characiformes: Characidae): classification and the evolution of reproductive traits". BMC Evolutionary Biology. 15 (1): 146. Bibcode:2015BMCEE..15..146T. doi: 10.1186/s12862-015-0403-4 . PMC   4509481 . PMID   26195030.
3. Da Silva, Y. (2013). "Blue-bellied fish is a surprise catch". Natural History Museum.
4. Mattox G, Britz R, Toledo-Piza M, Marinho M (2013). "Cyanogaster noctivaga, a remarkable new genus and species of miniature fish from the Rio Negro, Amazon basin (Ostariophysi: Characidae)". Ichthyological Exploration of Freshwaters. 23 (4): 297–318.
5. Kottelat M, Britz R, Tan HH, Witte K (2005). "Paedocypris, a new genus of Southeast Asian cyprinid fish with a remarkable sexual dimorphism, comprises the world's smallest vertebrate" (PDF). Proceedings of the Royal Society B: Biological Sciences. 273 (1589): 895–899. doi:10.1098/rspb.2005.3419. PMC   1560243 . PMID   16627273. Archived from the original (PDF) on 2009-07-12. Retrieved 2015-05-04.