HETEROTIS NILOTICUS PDF

Ehrenberg, scientist Ref. More on author: Cuvier. Also introduced in Madagascar Ref. Several countries report adverse ecological impact after introduction. Short description Morphology Morphometrics Dorsal spines total : 0; Dorsal soft rays total : ; Anal spines : 0; Anal soft rays : 34 - 39; Vertebrae : 66 - Elongated and robust body, its height 3.

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The African bonytongue H. This species is native to many parts of Africa, and has This species is native to many parts of Africa, and has also been introduced into many African rivers and lakes to increase fish production Micha, The hardiness of this fish, together with its high growth rate, make it a candidate for aquaculture in Africa and it has been transported to a number of countries for this purpose Welcomme, Escapees from ponds into the wild have resulted in the establishment of populations which can form the basis for fisheries Welcomme, Froese and Pauly say that several countries report adverse ecological impacts after introduction, but these ecological impacts were not specified.

Froese and Pauly also mention H. Bake and Sadiku describe a decline in the population density of H. Body rather elongate, its depth from 3. Head rather short, length 3. Elongated dorsal and anal fins are posteriorly positioned and end close to the small, rounded caudal fin Bailey, ; Dankwa et al.

Dorsal fin with , anal with , rays. Scale formula: 2. Dermal bones of skull deeply sculptured. Gill rakers thin and serrate, numbering 33 young to 98 on the ceratobranchial lower limb and 21 young to 76 on the epibranchial upper limb.

These numbers increase with the size of the fish. Number of vertebrae: average usually Maximum reported size: mm SL weight approx. Colour is uniformly greyish or bronze; lips yellowish and eye more or less golden.

According to some authors Daget, ; Blache et al. In the young, posterior parts of anal and dorsal fins sometimes marked with dark longitudinal bands, and scales with a dark oval spot at margins of overlapping zones Paugy, A description is also available in Fishbase Froese and Pauly, Reproductive organs are described in detail by Adite et al. It is generally accepted that the first introductions were made in the early s Moreau, Areas of introduction of H. Also introduced in Madagascar Stiassny and Raminosoa, The distribution in this summary table is based on all the information available.

When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

The complexity of the hydrological regime of many African river and lake systems enhances the risk of introduction and spread in related water bodies of the aquatic system. Migration from source population lakes during flooding favours the dispersal of Heterotis in related water bodies and therefore will increase the risk of introduction Adite et al.

Its importance as a candidate for aquaculture and fisheries also enhances the risk of introduction. Escapees from ponds into the wild resulted in established populations, which form the basis for fisheries Welcomme, It occurs in shallow water where it feeds on invertebrates, copepods and chironomids. Juveniles are found in swampy places among aquatic vegetation; adults live in the open water of rivers and lakes, where they can be found in the pelagic zone as well as the littoral zone Moreau, The species can survive in deoxygenated waters Moreau, ; Adite et al.

Carrera et al. They tested these primers with a sample of 40 individuals from two natural populations in Benin, West Africa. The number of alleles for the nine microsatellites ranged from 2 to 9, observed heterozygosity from 0.

No significant deviations from Hardy-Weinberg equilibrium or linkage disequilibrium were observed, and there is no indication of null alleles. Bonytongues H. Nests average cm in diameter range 77— cm and occur at an average water depth of 60 cm range 40—86 cm. Between 1 and 7 days posthatch, larvae have large yolk sacs and are incapable of significant movement, and thus are particularly vulnerable. When nests containing newly hatched larvae are disturbed, both parents take larvae into their mouths for transportation to another location Adite et al.

Tending of nests and broods occurs from the time of hatching until juveniles disperse from the nest. Recruitment age is estimated as 6 months Moreau, , the age at which Heterotis initiates migration from reproductive sites to open water or to floodplains. Consequently, the species displays a life history strategy that is closer to the equilibrium endpoint than the periodic endpoint Winemiller and Rose, , which implies that parental care is essential for early life stage survivorship and levels of recruitment needed for long term population viability Winkle et al.

Lowest and highest fecundities recorded for individual fish were mm TL, mm SL, 1. In Lake Oubangui, Micha reported fecundity between and 15, oocytes. Fecundity increased with body length and body weight. Ovarian weight increased with body size. The number of oocytes per gram of ovary was not influenced by body size.

Relative fecundity number of oocytes per gram of body mass revealed no general association with body size Adite et al.

GSI peaked during the wet season May to August , then declined progressively throughout the flood period until the beginning of the dry season in November to December. These indicated that the spawning period of bonytongues was restricted to the wet and flood period margins Adite et al.

Detailed descriptions of structure and development of reproductive organs are given by Adite et al. Reizer reported an age at maturity of 20 months for H. In Madagascar, H. Micha cited by Moreau reported a size at first maturity of mm g in Lake Oubangui.

The size at first maturity for H. In this aquatic system, body condition varied according to habitat lake vs river channel and season dry, wet, flood Adite et al. Possibly between 5 and 10 years Moreau, Moreau reported migration during reproduction.

A source subpopulation of H. The different food habits of Heterotis in different habitats suggest a degree of trophic plasticity of this species. The thick-walled gizzard of H. Lauzanne in Lake Chad recorded the diet of H. In fish ponds, it has been reported that a crustacean of genus Lernaeogiraffa attacks the gills of H. In fish farming in Ghana, the parasite Lernea has been found Micha, In Lake Ougbangui, the protozoa, Glossatella sp.

Sporozoa infection Myxobolus sp. No accidental introduction has been recorded. However, the high interconnection of African rivers and lakes systems leading to a complex hydrological regime could allow natural spread of H. For example in Benin, according to Froese and Pauly , H. However, it is also possible that its presence in this river may result from a natural introduction from adjacent water bodies. The first introductions were made in the s. In many African rivers and lakes, H. About tons of H.

Gbaguidi and Pfeiffer estimated the harvest of bonytongues in Benin at tons. Women buy H. Farming of H. Froese and Pauly report that several countries experience adverse ecological impacts after introduction, but these ecological impacts were not specified. More research is required to evaluate the impact of H. Fishing of H. Research on the exploitation of H. Nguenga and Brummett evaluate the establishment of H. Work in Nigeria includes the evaluation of aquaculture potential of H.

Preliminary results on the effects of weaning age on survival and growth of H. Problems for aquaculture development include artificial reproduction and larval rearing weaning. Like the African catfish Clarias gariepinus , Heterotis spawns during the flooding period during which both species are abundant. For both species, reproduction in captivity is difficult and both are omnivorous and feeding on benthic and pelagic prey Moreau, ; Adite et al.

Adite A, Adite A; Thielen RVan, Ecology and fish catches in natural lakes of Benin, West Africa. Fish, Environmental Biology of Fishes, Ecology of Freshwater Fishes, Aubenton F, Etude de l'appareil branchiospinal et de l'organe suprabranchial d' Heterotis niloticus Cuv.

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Human uses

The African arowana or Nile arowana Heterotis niloticus is a species of bonytongue. Despite being called an "arowana", the African arowana is more closely related to arapaimas , the only other members in the family Arapaimidae , [2] than the South American, Asian, and Australian arowanas in the family Osteoglossidae the Arapaimidae are sometimes included in the Osteoglossidae. Compared to these, the African arowana has a more terminal mouth and is the only one that feeds extensively on plankton. The African arowana is a long-bodied fish with large scales, long dorsal and anal fins set far back on the body, and a rounded caudal fin.

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African arowana

The African bonytongue H. This species is native to many parts of Africa, and has This species is native to many parts of Africa, and has also been introduced into many African rivers and lakes to increase fish production Micha, The hardiness of this fish, together with its high growth rate, make it a candidate for aquaculture in Africa and it has been transported to a number of countries for this purpose Welcomme, Escapees from ponds into the wild have resulted in the establishment of populations which can form the basis for fisheries Welcomme, Froese and Pauly say that several countries report adverse ecological impacts after introduction, but these ecological impacts were not specified. Froese and Pauly also mention H.

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African Arowana

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