Obscure snakehead

The obscure snakehead, Parachanna obscura, is a medium-sized carnivorous fish that has an elongated shape tapered on both ends and is covered in medium circular scales (cycloid).[3] The head, resembling a snake, is long and depressed anteriorly and covered with cycloid scales slightly larger than those scales on the body.[3] This species is found in central Africa along the western coastline from as far north as Senegal to as far south as Zaire and into central Africa into southwest Sudan.

Obscure snakehead

Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Anabantiformes
Family: Channidae
Genus: Parachanna
Species:
P. obscura
Binomial name
Parachanna obscura
(Günther, 1861)
Synonyms[2]
  • Ophiocephalus obscurus Günther, 1861
  • Channa obscura (Günther, 1861)
  • Channa obscurus (Günther, 1861)
  • Ophicephalus obscurus (Günther, 1861)
  • Paraphiocephalus obscurus (Günther, 1861)
  • Parophiocephalus obscurus (Günther, 1861)

Geographic range

Four identified Parachanna species originate within the continent of Africa. They include P. fayumensis (fossil), P. africana, P. insignis, and the most common, P. obscura.[3][4] P. africana is restricted to Benin, Nigeria, and into Gabon, P. insignis is found throughout the Congo River basin in Congo and into Gabon, and P. obscura is the most widespread of the African species, being found in the Lake Chad basin, and the Nile, Zaire, Cross, Niger, and Senegal River basins.[4]

Parachanna distribution

Morphology

Parachanna obscura is a medium-sized carnivorous fish with an elongated shape tapered on both ends, and is covered in medium circular scales (cycloid).[3] The head, resembling a snake, is long and depressed anteriorly and covered with cycloid scales slightly larger than those scales on the body.[3] The eyes are laterally located, large, and help the fish to locate its prey quickly.[3] Two pairs of nostrils occur on either side of the head. The mouth is large, and because the lower jaw is slightly longer than the upper jaw, the fish is able to thrust out its lower jaw (protract) to catch its prey.[3] The fish has two rows of teeth.[4] The outer row consists of small, sharp, conical teeth, and the inner row consists of four to six large canines.[3][4] P. obscura has a single lateral line.[4] The coloration of P. obscura adults and juveniles consists of dark blackish, rounded spots found along the flanks.[3] The ventral side of the fish has a yellowish, reddish, and brownish marbling coloration.[3] Dark spots on the back and lateral dark bands on the head help to define the fish. A baby fish initially has an ochre base coloration with a black stripe down its flank from the snout to the caudal fin.[3] P.obscura larvae are yellow in color.[3]

Habitat

The obscure snakehead is both benthopelagic (bottom dweller) and potamodromous (freshwater migratory), and thrives in harsh environments, including muddy waters.[3][4] This fish lives in streams, ponds, rivers, lakes, marshes, lagoons, swamps, and floodplains.[3][4] The obscure snakehead is also known as the “sleeping fish”, as it spends much of its time motionless among the aquatic vegetation.[5] It lives in waters greater than 20 °C and is found primarily within the intertropical convergent zone.[6]

Diet and growth

Obscure snakeheads are carnivorous fish. Adults feed primarily on other fish up to half their size, while juveniles feed on insect larvae, insects, prawns, and copepods.[7] This fish can gain about 2 g/day and reach a weight of 1 kg within 4–5 months.[3] An adult P. obscura has been measured at 54 cm.[6]

Reproduction

Determining the sex of the obscure snakehead can only be done through the dissection of the gonads.[3][8] Reproduction happens throughout the year, especially during and right after flooding. Males and females during spawning make a color change. The males change from brown to bright blue and the females' brown spots turn a deeper dark brown and the bright spots on their fins turn blue, and both male and female pectoral fins turn white at the tips.[3] The female lays her eggs and the male immediately fertilizes them. Incubation time varies depending on the temperature of the water and amount of light to which the eggs are exposed.[3] The adults both share in the responsibility of protecting the young until they reach a length of about 3 mm.[3]

Commercial importance

The obscure snakehead is being considered as an emerging aquaculture species in Africa. The fish is very fleshy, has few bones, and is high in protein.[9] The obscure snakehead also has some medicinal properties when eaten especially during recuperation from serious illnesses and as a postnatal diet.[9] Hardiness, rapid growth, tasty flesh, and commercial value of this species represent significant aquaculture potential.[3] An issue of concern is the way the fish are harvested. The use of poison, fire, and dynamite as fishing tools, along with the improper netting of fish, are hurting the fish population, as well as those humans consuming the fish.[10]

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References
  1. Moelants, T. (2010). "Parachanna obscura". IUCN Red List of Threatened Species. 2010: e.T183172A8064900. Retrieved 24 December 2019.
  2. Froese, Rainer and Pauly, Daniel, eds. (2019). "Parachanna obscura" in FishBase. August 2019 version.
  3. Kpogue, Diane N. S.; Mensah, Guy A.; Fiogbe, Emile D. (March 2013). "A review of biology, ecology and prospect for aquaculture of Parachanna obscura". Reviews in Fish Biology and Fisheries. 23 (1): 41–50. doi:10.1007/s11160-012-9281-7.
  4. Murray, Alison M. (July 2012). "Relationships and biogeography of the fossil and living African snakehead fishes (Percomorpha, Channidae, Parachanna )". Journal of Vertebrate Paleontology. 32 (4): 820–835. doi:10.1080/02724634.2012.664595. JSTOR 23251276.
  5. Kpogue, D. N. S.; Mensah, G. A.; Fiogbe, E. D. (2013). "A review of biology, ecology and prospect for aquaculture of parachanna obscura". Reviews in Fish Biology and Fisheries. 23 (1): 41–50. doi:10.1007/s11160-012-9281-7.
  6. Hurtley, S (2004). "Snakeheads: Coming down the mountains". Science. 304 (5676): 1415. ProQuest 213579765.
  7. Courtenay, W. R., & Williams, J. D. (2004). Snakeheads (Pisces, Channidae): A biological synopsis and risk assessment. Gainesville, FL: U.S. Dept. of the Interior, U.S. Geological Survey
  8. Bolaji, B. B.; Mfon, T. U.; Utibe, D. I. (2011). "Preliminary study on the aspects of the biology of snakehead fish Parachanna Obscura (Günther) IN A NIGERIAN WETLAND". African Journal of Food, Agriculture, Nutrition & Development. 11 (2): 4709–4717. doi:10.4314/ajfand.v11i2.65923.
  9. Ama-Abasi, D.; Affia, I. N. (2010). "Aspects of the biology of snakehead, parachanna obscura (gunther 1861) in the Cross River, Nigeria". Global Journal of Agricultural Sciences. 9 (2): 7–13. ProQuest 873638098.
  10. Inogwabini, Bila-Isia (2005). "Fishes of the salonga national park, democratic republic of congo: survey and conservation issues". Oryx. 39: 78–81. doi:10.1017/S003060530500013X.
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