Convict cichlid

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Convict cichlid
a female Archocentrus nigrofasciatus
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Actinopterygii
Order:
Perciformes
Family:
Cichlidae
Genus:
Archocentrus

(Gill 1877)
Species:
A. nigrofasciatus
Binomial name
Archocentrus nigrofasciatus
(Günther, 1867)

The Convict cichlid (Archocentrus nigrofasciatus) is a species of fish from the family Cichlidae native to Central America[1] also known as the zebra cichlid.[2] Convict cichlids are popular aquarium fish[1] and have also been the subject of a numerous of studies on fish behaviour.[3]

Appearance, size and sexual dimorphism

A young male convict cichlid showing the leucistic colouration

The wild-type of the species has 8-9 black vertical bars on a blue-grey body, along with a dark blotch on the operculum.[1] Juvenile convict cichlids are monomorphic until they reach sexual maturity. Unusually for fish, the female is more highly coloured.[4] Along with being smaller, female convict cichlids have more intensely coloured black bands across the body and have pink to orange colouration in the ventral region and on the dorsal fin.[5] In contrast, male convict cichlids are larger, have more pointed ventral, dorsal and anal fins which often extend into filaments. In addition, older males frequently develop vestigial fatty lumps on their foreheads.[5][6] The average standard length of breeding sized males in the wild ranged from 63-66 millimetres, while breeding sized females ranged from 42-55 millimetres.[4] The maximum standard length has been reported to be 100 millimetres, with total length near 120 millimetres.[1][7] Body weight has been reported to range from 34-36 grams (1.2-1.3 oz).[1] Selective breeding has resulted in a leucistic strain of convict cichlids[5] variously known as white convicts, pink convicts, gold convicts and A. nigrofasciatus "Kongo"[6], the dark barring of the wild type is absent in the leucistic strain.[1] The leucistic colouration is caused by a mutation in an autosomal gene and is recessively inherited.[8]

Diet

In natural habitats, the species feeds on crustaceans, small fish, insects, various worms along with higher plants and algae.[9] It has been demonstrated in laboratory studies that social status and associated stress can effect digestive function in convict cichlids.[10]

Taxonomy

The species originally was described in 1867 by Albert Günther after having been collected in Central America by Frederick DuCane Godman and Osbert Salvin.[11] A number of synonyms exist for this species including: Cichlasoma nigrofasciatus, Cryptoheros nigrofasciatus and Heros nigrofasciatus.[12][13]

Etymology

The common name convict cichlid is, like the species name, derived from the vertical black stripes on the fishes body and their similarity to the striped prison uniforms of British convicts. Similarly, the species epithet nigrofasciatus literally means black-striped.

Distribution and habitat

A male convict cichlid caught on a hook and line, in the heated outflow of a coal powerplant in Victoria, Australia.

Convict cichlids are endemic to the lake and streams of Central America. In particular, the species occurs along the eastern coast of central America from Guatemala to Costa Rica, while on the western coast from Honduras to Panama.[1] Convict cichlids prefer moving water, and are most frequently found in habitats with cover in the form of rocks or sunken branches.[14] Convict cichlids are relatively tolerant of cooler water, an ability which has allowed the species to colonise volcanic lakes at elevations of 1500 m (4920 feet).[15] At four natural habitats of the convict cichlid in Costa Rica the pH was found to range from 6.6 - 7.8, while alkalinity ranged from 63 to 77 ppm CaCO3. The daily water temperature ranged from 26-29 ºC (79-84 ºF).[4]

Feral populations

The species also occurs outside its natural range in Australia, in the warm effluent of power stations in Victoria, and also in tropical Queensland.[16] In addition the species has been introduced to Réunion[1], Japan[1], Mexico[13], and the USA.[17][18]

Reproduction

a male convict cichlid

Like most cichlids, convicts have prolonged brood care of both eggs and free-swimming fry.[19] The species can reach sexual maturity as young as 16 weeks of age, though sexual maturity is more commonly reached by 6 months.[15] Sexually mature convicts form monogamous pairs and spawn in caves or crevices, like other Archocentrus species, eggs are laid on the upper surface of the cave and are adhesive. In the wild caves are frequently dug underneath large stones.[4] After fertilisation the eggs take approximately 72 hours to hatch, a further 72 hours is required for the larvae to absorb their yolk sacs and allow fin development prior to the fry becoming free-swimming.[20] While in this free swimming stage fry feed and forage during daylight in a dense school and return to the cave or crevice during the night.[21] Both parents are involved in guarding the fry from brood predators and engage in behaviours to assist feeding such as moving leaves or fin digging.[4] Brood care of eggs, larvae and free-swimming juveniles in the wild can last 4-6 weeks, [4] and occurs only once per season for the majority of females.[4] In contrast, females in aquariums are known to breed many times per year with short intevals of 12-13 days between broods.[22] In captivity, breeding pairs of convict cichlids have been demonstrated to adopt similarly aged fry from other parents.[23] In other cichlids it has been suggested this behaviour may reduce predation on the fry belonging to the adoptive parents,[24] though whether this is the case for A. nigrofasciatus remains unknown.

Geographic variants

a pair of A. nigrofasciatus collected in Bocas del Toro, Panama

The convict cichlid does display significant variation in colouration across its range in Central America.[25][26] Some of these regional variants may be different species, scientific investigations of the taxonomy of these morphs have yet to be undertaken. In the cichlid keeping hobby, one such fish Archocentrus aff. nigrofasciatus "Honduran Red Point" was collected from a stream in Honduras by Rusty Wessel.[27][28] Aquarium care of these fish is similar to that of standard aquarium strains of A. nigrofasciatus.[28]

In the aquarium

Convict cichlids are easily maintained and bred in aquariums.[5][6] The aquarium should be decorated to mimic the natural environment and should include rocks and artificial caves for breeding.[5] The species is an unfussy omnivore and most types of prepared fish foods are readily accepted. The species will also consume aquarium plants.[5][6] Convict cichlids are aggressively territorial during breeding and pairs are best kept alone in suitably sized aquariums. It has been suggested that brood care is reduced in aquarium strains.[5][6] Due to the tendency of the species to dig, external filtration is recommended over undergravel filter systems.[15] The relatively small size, ease of keeping and breeding makes the convict cichlid an ideal cichlid for beginner and advanced aquarists interested in observing brood care in cichlids in the aquarium.[15]

See also

References

  1. ^ a b c d e f g h i Froese, R. and D. Pauly. Editors. "Archocentrus nigrofasciatus, Convict cichlid". FishBase. Retrieved 2007-03-29. {{cite web}}: |author= has generic name (help)
  2. ^ ITIS Report. "Archocentrus nigrofasciatus". Integrated Taxonomic Information System. Retrieved 2007-03-30.
  3. ^ Robins CR, Bailey RM, Bond CE, Brooker JR, Lachner EA, Lea RN, Scott WB (1991) World fishes important to North Americans. Exclusive of species from the continental waters of the United States and Canada. Am. Fish. Soc. Spec. Publ. 21: p. 243.
  4. ^ a b c d e f g Wisenden BD (1995) Reproductive behaviour of free-ranging convict cichlids, Cichlasoma nigrofasciatum Environmental Biology of Fishes 43: 121-134.
  5. ^ a b c d e f g Riehl, Rüdiger. Editor. (1996. 5th Edn.). Aquarium Atlas. Germany: Tetra Press. ISBN 3-88244-050-3. {{cite book}}: |first= has generic name (help); Check date values in: |year= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  6. ^ a b c d e Sands D (1994) A fishkeepers guide to Central American cichlids. Tetra Press. Belgium pg 59-60.
  7. ^ Kullander, S.O., 2003. Cichlidae (Cichlids). p. 605-654. In: R.E. Reis, S.O. Kullander and C.J. Ferraris, Jr. (eds.) Checklist of the Freshwater Fishes of South and Central America. Porto Alegre: EDIPUCRS, Brasil.
  8. ^ Itzkovich J, Rothbard S, Hulata G (1981) Inheritance of pink body colouration in cichlasoma nigrofasciatum Günther (Pisces, Cichlidae). Genetica 55: 15-16.
  9. ^ Mills D, Vevers G (1989) The Tetra encyclopedia of freshwater tropical aquarium fishes. Tetra Press, New Jersey.
  10. ^ Earley RL, Blumer LS, Grober MS (2004) The gall of subordination: changes in gall bladder function associated with social stress Proceedings of the Royal Society B: Biological Sciences 271: 7-13.
  11. ^ Günther A (1867) On the fishes of the states of Central America, founded upon specimens collected in fresh and marine waters of various parts of that country by Messrs. Salvin and Godman and Capt. J. M. Dow. Proc. Zool. Soc. Lond. 600-604.
  12. ^ Froese, R. and D. Pauly. Editors. "Archocentrus nigrofasciatus, synonyms". FishBase. Retrieved 2007-03-30. {{cite web}}: |author= has generic name (help)
  13. ^ a b Juan Miguel Artigas Azas. "Cryptoheros nigrofasciatus (Günther, 1867)". The Cichlid Room Companion. Retrieved 2007-03-30.
  14. ^ Conkel, D (1993) Cichlids of North and Central America T.F.H. Publications, Inc., USA.
  15. ^ a b c d Loiselle, Paul V. (1995). The Cichlid Aquarium. Germany: Tetra Press. ISBN 1-56465-146-0. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)
  16. ^ Koehn JD, MacKenzie RF (2004) Priority management actions for alien freshwater fish species in Australia. New Zealand Journal of Marine and Freshwater Research 38: 457–472.
  17. ^ Yamamoto MN, Tagawa AW (2000) Hawai'i's native and exotic freshwater animals. Mutual Publishing, Honolulu, Hawaii. p. 200
  18. ^ Page LM, Burr BM (1991) A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston. p. 432
  19. ^ Keenleyside MHA (1991) Parental Care. In: Cichlid Fishes: behaviour, ecology and evolution Chapman and Hall, London. p. 191-208.
  20. ^ Noakes DLG (1991) Ontogeny of behaviour in cichlids. In: Cichlid Fishes: behaviour, ecology and evolution Chapman and Hall, London. p. 209-224.
  21. ^ Wisenden BD (1994) Factors affecting male mate desertion in the biparental cichlid fish (Cichlasoma nigrofasciatum) in Costa Rica. Behavioral Ecology 5: 439-447.
  22. ^ Wisenden DB (1993) Female convict cichlids adjust gonadal investment in current reproduction in response to relative risk of brood predation. Canadian Journal of Zoology 71: 252-256.
  23. ^ Espmark Y, Knudsen T (2001) Intraspecific brood adoption in the convict cichlid with respect to fry of two colour morphs Journal of Fish Biology 59: 504–514.
  24. ^ Nelson CTJ, Elwood RW (1997) Parental state and offspring recognition in the biparental cichlid fish Pelvicachromis pulcher. Animal Behaviour 54: 803-809.
  25. ^ Heijns W (2001) A convict from the Volcano Cichlid Room Companion Ed. Juan Miguel Artigas Azas.
  26. ^ Azas JMA (2002) Cryptoheros, The Small Central American Cichlids Cichlid Room Companion Ed. Juan Miguel Artigas Azas.
  27. ^ Wessel R (2006) The Honduran Red Point: A beautiful blue convict-type species from Honduras Tropical Fish Hobbyist 54: 104-106.
  28. ^ a b Borstein R (2005) Archocentrus sp. "Honduran Red Point" Greater Chicago Cichlid Association
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