International Journal of Fisheries and Aquatic Studies 2020; 8(1): 99-109

E-ISSN: 2347-5129 P-ISSN: 2394-0506 (ICV-Poland) Impact Value: 5.62 Fish diversity of four waterways of left bank of Alima (GIF) Impact Factor: 0.549 IJFAS 2020; 8(1): 99-109 River in , Congo © 2019 IJFAS www.fisheriesjournal.com Received: 16-11-2019 Isabelle Mady-Goma Dirat, Anthelme Tsoumou, Louis Regis Dossou- Accepted: 18-12-2019 Yovo, Léon Akoua, Marceline Mikia, Durelle Brith C, Olabi-Obath and Isabelle Mady-Goma Dirat Joseph Vouidibio Research Laboratory of Biology and Ecology, ENS Marine N’ Gouabi University, Abstract Brazzaville, Congo The inventory of the ichthyo fauna of the Alima watershed was carried out in four rivers of Boundji district (Angouewele River, Engondo River, Andouwou River and Amegni River). Fishes were captured Anthelme Tsoumou with cast nets, gill nets, rotenone and drain fishing shows a species richness of 52 species, belonging to Research Laboratory of Animal 36 , 21 families and 10 orders. Three orders were more represented in all rivers: Siluriformes Biology and Ecology, ENS (31%), (28%) and (11.32%). Mormyridae (20.75%), Cichlidae Marine N’ Gouabi University, (9.48%) and Claroteidae (9.44%) were the most common families. The Mormyridae was the most Brazzaville, Congo diversified with 11 species. Angouewele, Amegni and Engondo have the most diversified and balanced populations with diversity index values between 3.24 and 3.96 and equitability between 0.71 and 0.81. Louis Regis Dossou-Yovo Andouwou on the other hand, was the least diversified with 2.97 and an equitability of 0.66. The Research Laboratory of Animal presence of species such as Pollymyrus sp., Raïamas chrysti, Raïamas buchholzi, Mastacembelus sp. Biology and Ecology, ENS more oxygen consumers, proves that the waters of these courses are still of good quality. The fish Marine N’ Gouabi University, Brazzaville, Congo inventories must continue on the middle and upper courses of the Alima River.

Léon Akoua Keywords: Boundji district, Congo basin, biodiversity, Shannon index, equitability Research Laboratory of Animal Biology and Ecology, ENS 1. Introduction Marine N’ Gouabi University, An astonishing diversity of freshwater fish species is found in Africa, however, 21% of Brazzaville, Congo continental African freshwater species are threatened with extinction [1]. The ichthyofauna of

Marceline Mikia the right bank of the Congo Basin is poorly known. The Congo basin is the subject of very few Research Laboratory of Animal studies, especially on its right bank. Indeed, poorly known Congolese aquatic ecosystems are Biology and Ecology, ENS threatened by population growth and deforestation [2]. Also, intensive fisheries and other Marine N’ Gouabi University, natural disturbances (drought and silting) or anthropogenic (erection of dams, pollution, Brazzaville, Congo reduction of habitat). In Congo, the potential for inland fisheries has been estimated at more [3] Durelle Brith C than 100,000 tons per year . The quantity of freshwater fish caught in the Cuvette [3] Faculty of Sciences and Department is about 13,000 tons . These scarce studies, prove that the ichthyofauna of the Techniques, Marine N’ Gouabi tributaries of the right bank of the Congo basin must be better investigated to help better University, Brazzaville, Congo management. The information available is the extensive systematic work [4, 5]. A few partial studies, mostly old, were carried out on Alima River, Sangha River [6, 7] and the right bank of Olabi-Obath [8] Faculty of Sciences and Middle Congo . Later, Later, preliminary observations have been made in some rivers on the [9] Techniques, Marine N’ Gouabi right bank of Congo basin : in Likouala aux Herbes River and Lake Tele ; in Mambili River University, Brazzaville, Congo in Odzala National Park [10]; on the lower course of Alima River [11]; in Likouala aux Herbes [12]; in Lefini River [13]; in Djiri River [14]; in Tsieme River [15]; in the right bank of Malebo Pool Joseph Vouidibio [2, 16]; in Mfilou River and the Djoue River [17, 18]; in Komo River [19]; in Dzoumouna River and Faculty of Sciences and [20, 21] Techniques, Marine N’ Gouabi Loua River . Therefore, the present study has conducted to know ichthyologic diversity of University, Brazzaville, Congo the Alima watershed of four rivers in Boundji district. Moreover, the species richness was determined according to different fishing techniques useddevelopment, status of digestion ability is a mystery. Therefore, a good understanding of fish.

Corresponding Author: Isabelle Mady-Goma Dirat 2. Materials and Methods Research Laboratory of Animal 2.1 Presentation of the study environment Biology and Ecology, ENS The district of Boundji is located in the . Its area is 2600 km² for a Marine N’ Gouabi University, population of 11695 inhabitants; a density of 4.41 inhabitants / km² (Anonymous, 1980). Brazzaville, Congo ~ 99 ~ International Journal of Fisheries and Aquatic Studies http://www.fisheriesjournal.com

It is, limited to the northwest by Owando District, to the east waterway is located at 15 ° 20.299 East and 0.03309 South, by Ewo District, to the south by Okoyo District and to the this point located next to the bridge, as shown in Figure 3. west by Abala District. Boundji District is located about 120 Engondo is a small village located at 15 Km from Boundji on km southwest of Owando and 50 km west of the National the Okoyo road, the fishing site on Engondo River (Station 2) Road Number 2 connecting Brazzaville to Ouesso, as shown is located two kilometres from the village: 015 ° 17.487 East in Figure 1. The waterways explored in this study are the and 01 ° 03.637 South. The fishing site on Andouwou River tributaries of the Alima basin. They flow through the forest, (station 3) is located one kilometre from the village Odikango, their dimensions including width and depth are variable, 15 ° 15.936 East and 1 ° 04903 South, between Odikango depending on the season. The average width does not exceed village and Engondo village, which are separated by 10 ten (10) meters. The depth varies between sixty 0.6 meters in kilometers. Like other rivers, Andouwou fishing site serves the dry season and 1.20 meters in the rainy season. These four both as a place for retting cassava and bathing. It flows rivers (Angouewele, Engondo, Andouwou, and Amegni) were through a ridiculous forest. The last fishing site is on Amegni selected according to their accessibility. The fishing site on River (station 4), 10 kilometers from Odikango village, has Angouewele River (Station 1) is located just outside the town not been georeferenced. of Boundji, going on the Okoyo road. This fishing site on this

Fig 1: Representative map of the study area (Kempena, 2019)

2.2 Physico-chemical parameters (one species) and maximum when all species have equal Four physico-chemical parameters of surface water (pH, frequencies. The boundaries of this index vary with the temperature, conductivity and TDS) were measured using a species richness (S) and the frequencies (pi) that are not actual multipara meter brand Combo. frequencies in the stand. The equitability which is the ratio of the real diversity to the 2.3 Sampling and fish conservation maximum diversity was calculated. It is represented by the Fishes caught using cash nets, gillnets, rotenone and drain following formula: fishing, were fixed with formalin 10% and then stored in formalin 5% or alcohol 70%. The fish identification was made using the keys determination proposed by different authors [22, 23, 24, 25, 26, 27, 28, 29, 30].

H max: lnS; 2.4 Diversity indexes H ': real diversity; The species richness study has made it possible to calculate H max: maximum diversity; the diversity of the populations of fishes caught [31]. For this, S: species number. we used the Shannon-Weaver index (H').

H' = - pi Log2 pi 2.5 Similarity index pi = Ni / N T Duellman's similarity index allows us to say whether the Ni: number of species I; ichthyofaunic groupings of the four waterways studied belong N : total population size. T to the same animal community. This is the measure of the The Shannon-Weaver index measures indeterminacy in the degree of similarity of the different waterways. It is given by population structure. It is zero if the determination is complete the formula: ~ 100 ~ International Journal of Fisheries and Aquatic Studies http://www.fisheriesjournal.com

2.6 Statistical analysis A Cluster analysis based on Euclidean distance is performed from the species richness - rivers matrix to identify A: total number of species in group 1 similarities between the different rivers. B: total number of species in group 2 C: total number of species common to both groups. 3. Results and discussion If K is greater than 50%, the compared groupings represent 3.1 Physico-chemical parameters of surface water the same community. Some physico-chemical parameters of surface water were

recorded (Table 1).

Table 1: Physico-chemical parameters of surface water

Dry season Rainy season Waterway T °C pH Cond μS/cm TDS T °C pH Angouewele 26,6 5,97 1,8 0,66 28,5 6 Engondo 26,6 5,5 - - 27,7 6,1 Andouwou 25,6 5,60 1 0 27,5 6,2 Amegni 25,8 5,65 - - 27,8 6

The temperature of the surface water varies according to the indicates a low mineralization of the soils of the study area. seasons, the low temperatures are observed in dry season Low values of pH, conductivity and TDS were also found in where the temperature varies between 25, 8 °C and 26,6 °C. several tributaries of the right bank of the Congo basin [32]. They vary between 27.5 °C and 28.5 °C in the rainy season. The pH is slightly more acidic in the dry season than in the 3.2 Species composition rainy season. In all rivers, the pH values vary between 5.5 in The study of the fish biodiversity of Fours Rivers of Alima the dry season and 6.2 in the rainy season. The TDS values watershed allowed identification of 52 species, 36 genus, 21 are very low (Angouewele: 0.66 NTU and Andouwou: 0.66 families, and 10 orders. Each species is designated by its local NTU). The same is true of the conductivity which is equal to name in M bochi language (Table 2). 1.8 μS/cm at Angouewele and 0 μS/cm at Andouwou, which

Table 2: List of species of the four rivers

Ordres Families Species Local name in Mbochi Lepidosireniformes Protopteridae 1-Protopterus dolloi Boulenger, 1900 Niombo 2-Polypterus retropinnus Boulenger, 1911 Konga Polypteriformes Polypteridae 3-Polypterus weeksi Boulenger, 1898 Konga Pantodontidae 4-Pantodon buchholzi Peters, 1877 Itsatsâ Notopteridae 5-Xenomystus nigri (Günther, 1868) Lépê 6-Gnathonemus petersii (Günther, 1862) Lébouwè 7-Marcusenius kutuensis (Boulenger,1899) Lébouwè 8-Marcusenius moorii (Günther, 1867) Lébouwè 9-Mormyrops nigricans Boulenger, 1899 Lébouwè 10-Mormyrops zanclirostris (Günther,1867) Lébouwè Osteoglossiformes Mormyridae 11-Mormyrops sirenoîdes Boulenger, 1898 Lébouwè 12-Petrocephalus ballayi Sauvage, 1883 Lébouwè 13-Petrocephalus sp Lebouwè 14-Petrocephalus christyi Boulenger, 1920 Lébouwè 15-Stomacorhinus sp Lébouwè 16-Polliymyrus sp Lébouwè Phractolaemidae 17-Phractolaemus ansorguii Boulenger, 1901 Okissi 18-Raïmas chrystyi Boulenger, 1920 Elô Cyprinidae 19-Barbus sp cf holotaenia (Boulenger 1904) Elôy’ombossi 20-Raïmas buchholzi (Peters, 1877) Elô Hespéride 21-Hepsetus odoe (Bloch, 1794) Mouénguè 22-Alestes liebrechtsii Boulenger, 1898 Okobi 23-Brycinus imberi Peters, 1852 Engondokoro Characiformes Alestidae 24-Bryconaethiops boulengeri Pellegrin, 1900 Letsuèlè 25-Phenacogrammus interruptus (Boulenger,1899) Lendzâ Distichodontidae 26-Xenocharax spilurus Günther, 1867 27-Auchenoglanis sp Mboka 28-Chrysichthys punctatus Boulenger, 1899 Ibarabara Claroteridae 29-Chrysichthys thonneri Steindachner, 1912 Ibarabara 30-Parauchenoglanis punctatus (Sauvage, 1879) Ikagna Siluriformes 31-Parauchenoglanis sp Ikagna 32-Schilbe yangambianus Ihèlèlè Schilbeidae 33-Schilbe marmoranthus Boulenger, 1911 Ilangwa Amphiliidae 34-Phractura lindica Boulenger, 1902

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35-Clarias buthupogon Sauvage, 1879 Ngolo 36-Clarias gariepinus (Burchell, 1822) Ibongo Clariidae 37-Clarias sp Ngolo 38-Channallabes apus (Günther, 1873) Omgabiri Malapteruridae 39-Malapterus electricus (Gmelin, 1789) Nina 40-Synodontis nigriventis David, 1936 Ikô la pèli Mochokidae 41-Synodontis contractus Vinciguerra, 1928 Ikô 42-Synodontis schoutedeni David, 1936 Ikô Aplocheilidae 43-Epiplatis sp Ombongo 44-Hemichromis élongeâtes (Guichenoti, 1859) Ikiè 45-Pelmatochromis nigrofasciatus (Pellegrin, 1900) Ikiè Labriformes Cichlidae 46-Tylochromis sp legnendè 47-Tilapia zillii (Gervais, 1848) Mbô Channidae 48-Parachanna insignis (Sauvage, 1884) Tsinga Anabantidae 49-Ctenopoma nanum Günther, 1896 Lékâ 50-Mastacembelus congicus Boulenger, 1896 Ossoua Mastacembelidae 51-Mastacembelus niger Ossoua 52-Mastacembelus sp Ossoua 10 21 52

3.3 Species richness of orders and families least represented. The Mormyridae (22%) is the most Figures 2a and 2b show the species richness of orders and representative family, followed by Claroteidae (10%), families for all catches. In the four rivers, the of Alestidae, Clariidae and Cichlidae (8%). The other families Siluriformes (31%) is the most represented, followed by had proportions between 6% and 2%. The specific Osteoglossiformes (27%), Characiformes (11%), Labriformes distribution of fishes in each river is shown in Table 3. The (7%), Cypriniformes (6%), Polypteriformes and same orders and families were also identified by many Anabantiformes (4%). Lepidosireniformes, authors in different proportion in the main tributaries of the Cyprinodontiformes and Synbranchiformes (2%) were the Congo basin [22, 23, 33, 10, 11, 2, 16, 19, 13, 14, 15, 17, 18, 34, 35].

Mormyridae 2% 2% Claroteidae 4% 2% 2% Siluriformes 4% 2% Alestidae Osteoglossiformes 14% 2% 22% Clariidae 6% 31% Characiformes 2% Cichlidae 6% Labriformes Cyprinidae 7% 10% Cypriniformes Mchokidae 6% 11% Polypteriformes 8% Polypteridae 6% 27% Anabantiformes 4% 8% 8% Schilbeidae Lepidosireniformes Protopteridae Pantodontidae Cyprinodontiformes 4% Notopteridae Synbranchiformes Phractolaemidae Hepsetidae Autres

Fig 2a: Species richness of orders Fig 2b: Species richness of families

Table 3: Fish species distribution according to the river

Orders Families Species R1 R2 R3 R4 Lepidosireniformes Protopteridae Protoptères dolloi, Boulenger, 1900 + - - + Polypteriformes Polypteridae Polyptères retropinnus Boulenger, 1911 - - - + Polyptères weeksi Boulenger, 1898 + - - - Pantodontidae Pantodon buchholzi Peters, 1877 ++ - - + Notopteridae Xenomystus nigri (Günther, 1868) + + ++ + Gnathonemus petersii (Günther, 1862) + - - - Marcusiens kutuensis (Boulenger, 1899) + - - - Marcusiens moorii (Günther, 1867) + + - + Mormyres nigricans Boulenger, 1899 - + + + Mormyrops sirenoîdes, Boulenger, 1898 - - + + Osteoglossiformes Mormyridae Mormyrops zanclirostris (Günther, 1867) - + + +

Petrocephalus ballayi, Sauvage, 1883 + + - + Petrocephalus christyi Boulenger, 1920 - + - - Petrocephalus sp Marcusen, 1854 - + - + Pollymerus sp (Traverne, 1971) +++ - - - Stomacorhinus sp, + - - - Phractolaemidae Phractolaemus ansorgii Boulenger, 1901 - + - -

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Barbus sp (cf holotaenia (Boulenger 1904) +++ +++ + + Cypryniformes Cyprinidae Raïamas buchholzi (Peters, 1877) +++ +++ - -

Raïamas chrystyi, Boulenger, 1920 +++ - - - Hepsetidae Hepsetus odoe (Bloch, 1794) + - - - Alestes liebrechtsii Boulenger, 1898 + - - - Characiformes Alestidae Brycinus imberi Peters, 1852 + - - - Bryconaethiops boulengeri Pellegrin, 1900 + - - - Phenacogrammus interruptus (Boulenger,1899) + - - - Distichodontidae Xenocharax spilurus Günther, 1867 + - - - Auchenoglanis sp - - + - Chrysichthys punctatus Boulenger, 1899 + - - - Claroteidae Chrysichthys thonneri Steindachner, 1912 + - - - Parauchenoglanis punctatus (Sauvage,1879) + + + + Parauchenoglanis sp + - + - Schilbeidae Schilbe marmoranthus Boulenger, 1911 +

Schilbe yangambianus (Poll, 1954) - ++ +

Siluriformes Amphiliidae Phractura lindica Boulenger, 1902 + + + + Clarias buthupogon Sauvage, 1879 + +++ +++ + Clariidae Clarias gariepinus (Burchell, 1822) + - + - Clarias sp - - ++ - Channallabes apus (Günther, 1873) - - + - Malapteruridae Malapterus electricus (Gmelin, 1789) - - + + Synodontis schoutedeni Davaid, 1936 + - - - Mochokidae Synodontis contractus Vinciguerra, 1928 + - - -

Synodontis nigriventis David, 1936 - - - + Cyprinodontiformes Aplocheilidae Epiplatis sp ++ - + + Hemichromis elongatus (Guichenot,1859) +++ ++ +++ + Cichlidae Labriformes Pelmatochromis nigrofasciatus(Pellegrin, 1900) + - - -

Tilapia zillii (Gervais, 1848) + - - -

Tylochromis sp + - - - Anabantidae Ctenopoma nanum, Günther, 1896 - + - + Anabantiformes Channidae Parachanna insignis (Sauvage, 1884) - - + + Mastacembelus congicus Boulenger, 1896 + + + - Synbranchiformes Mastacembelidae Mastacembelus niger - +++ +++ ++ Mastacembelus sp + - + - 10 21 52 35 18 21 22 R1=Angouewele River; R2=Engondo River; R3=Andouwou River; R4=Amegni River Absence: -; Presence: +; 1 to 10 specimens; ++: 11 to 20 specimens; +++: 21 and over

The Angouewele River had the highest species richness with technique (Table 4). Cash net and rotenone fisheries had 35 species, followed by Amegni River (22 species) and captured more species than drain fishing and gillnets (Figure Andouwou River (21 species). Engondo River is the least rich 3). However, there are species caught with the four of the four rivers with 18 species. The different fishing techniques: Hemichromis elongatus, Pantodon buchholzi, techniques practiced in each waterway partly explains these Xenomystus nigri, Mormyrops zanclirostris, Raïamas results. Indeed, in addition gillnet and cash net were used buchholzi, Parauchenoglanis punctatus, Clarias buthupogon, much more in Angouewele River. This waterway is the and Ctenopoma nanum. In addition, table 3 shows that some deepest and widest of all rivers. species were more easily captured by drain fishing or rotenone, these are Mastacembelus sp, Clarias sp and 3.4 Distribution of fish species by waterway according to Channallabes apus. fishing technique The fish surveyed were divided by waterway and fishing

Table 4: Fish species caugth according to fishing technique

Species Rivers Angouewele Engondo Andouwou Amegni FD FE Vd RT Vd RT Vd FD R T Vd Protopterus dolloi, Boulenger, 1900 ------+ - Polypterus retropinnus Boulenger, 1911 ------+ - Polypterus weeksi Boulenger, 1898 + ------Pantodon buchholzi, Peters, 1877 - - + - - - + + + + Xenomystus nigri (Günther, 1868) + ------+ + + Gnathonemus petersii (Günther,1862) - - - + ------Marcusenius kutuensis (Boulenger, 1899) + ------Marcusenius moorii (Günther, 1867) - + - + - - - - - + Mormyrops nigricans Boulenger, 1899 - - - + - - + - + + Mormyrops sirenoïdes - - - - - + - - + - Mormyrops zanclirostris (Günther, 1867) - - - + + + + + - +

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Petrocephalus ballayi Sauvage, 1883 - + - + - - - - - + Petrocephalus christyi Boulenger, 1920 - - - + ------Petrocephalus sp - - - + - - - - + - Pollymerus sp (Traverne, 1971) - + ------Stomatorhinus sp - + ------Parachanna insignis (Sauvage, 1884) - - - - - + - - + - Phractolaemus ansorguii (Boulenger, 1901) - - - - - + + - - - Barbus cf holotaenia (Boulenger, 1904) + + - + - - + - - + Raïamas buchholzi (Peters, 1877) + + + + ------Raïamas chrystyi Boulenger, 1920 - + + ------Hepsetus odoe (Bloch, 1794) + + ------Alestes liebrechtsii Boulenger, 1898 + ------Brycinus imberi Peters, 1852 + ------Bryconaethiops boulengeri Pellegrin, 1900 + ------Phenacogrammus interruptus (Boulenger, 1899) + ------Xenocharax spilurus Günther, 1867 + ------Auchenoglanis sp - - - - - + - - - - Chrysichthys punctatus Boulenger, 1899 - - + ------Chrysichthys thonneri Steindachner, 1912 - + ------Parauchenoglanis punctatus (Sauvage, 1879) + + + + - + - - + - Parauchenoglanis sp - + - - - - + - - - Schilbe marmoratus Boulenger, 1911 - + ------Schilbe yangambianus (Poll,1954) - - - + - - - - + + Phractura lindica Boulenger, 1902 - - - + - - + - - + Clarias buthupogon Sauvage, 1879 + - - + + + - + + + Clarias gariepinus (Burchell, 1822) - - + - - + - - - - Clarias sp - - - - - + + - - - Channallabes apus (Günther, 1873) - - - - - + - - - - Malapterus electricus (Gmelin, 1789) - - - - - + - - + - Synodontis schoutedeni David, 1936 ------Synodontis contractus Vinciguerra, 1928 - - + ------Synodontis nigriventris David, 1936 ------+ - Epiplatis sp - - + - - - + - + - Hemichromis elongatus (Guichenot, 1859) + + + + + + + - - + Pelmotochromis nigrofasciatus (Pellegrin, 1900) - + ------Tilapia zillii (Gervais, 1848) - + ------Tylochromis sp + + - + ------Ctenopoma nanum Günther, 1896 ------+ + + + Mastacembelus congicus Boulenger, 1896 - - + - + + + - - - Mastacembelus niger - - - + - - - - + + Mastacembelus sp - + ------Total = 52 15 16 10 16 4 13 12 5 16 13 FD = gillnet; FE = cash net; Vd = drain fishing; RT = rotenone

ANGOUEWELE ENGONDO 16 16 16 15 16

14 14 12 10 12 10 10 8 8 6

Species richness Species 6

4 richness Species 4 4 2 2 0 Gillnet Cash net Drain fishing 0 Fishing techniques Rotenone Drain fishing

Fishing techniques

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ANDOUWOU AMEGNI 16 14 13 16 12 12 14 13

10 12

8 10 richeness 8 6 5

Species Species 4 6 Species richness Species 4 2 2 0 Rotenone Drain fishing Gillnet 0 Fishing techniques Rotenone Drain fishing Fishing techniques

Fig 3: Species richness of each river according to fishing techniques

3.5 Species richness of orders in the four rivers least represented orders are Labriformes, Cyprinodontiformes, The species richness according to orders is represented by Cypriniformes and Anabantiformes, each of which is 5%. In Figure 4. In Angouewele River, Osteoglossiformes and Amegni River, Osteoglossiformes (36%) represent the richest Siluriformes (25%) dominated, followed by Characiformes order in species, followed by the Siluriformes (27%). (17%), labriformes (11%) and Cypriniformes (8%). Anabantiformes (9%), Labriformes, Cypriniformes, Synbranchiformes are poorly represented with 5%. The, Synbranchiformes, Polypteriformes, Lepidosireniformes and Cyprinodontiformes, Polypteriformes and Lepidosireniformes Cyprinodontiformes are the least represented (5%). In the were the least represented with 3%. The species richness of Congo basin, Teugels and Guegan (1994) found the same orders in Engondo River, which had only six orders, showing orders in varying proportions: Siluriformes (23.5%), that the Osteoglossiformes (41%) are the most represented. (18.7%), Osteoglossiformes (16.5%), They are followed by Siluriformes (23%), Cypriniformes and Cypriniformes (16.3%), Characiformes (14.3%). in Mambili Synbranchiformes (12%). The least represented orders were River [10]; in Likouala aux Herbes River [12]; in Djiri River [14]; the Labriformes and the Anabantiformes (6%). Andouwou in Alima River [11]; in Malebo Pool (Congo River) [2,16] River has 7 orders among which the order of Siluriformes is showed the predominance of the same orders in a specific the most represented, with 45%. It is followed by distribution in each river. Osteoglossiformes (20%) and Synbranchiformes (15%). The

Fig 4: Proportional distribution of species richness of orders in each river

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3.6 Species richness of families according to the waterway In Amegni River, the Mormyridae family (29%) is by far the The Figure 5 shows the proportional distribution of species most representative. The other families are poorly represented richness of families in Angouewele River, Engondo River, at 5%. Family-specific wealth in Angouewele, Engondo, and Andouwou River and Amegni River. Four families were Amegni ranks Mormyridae at 28.57%, 27.28%, and 43.75% dominant in Angouewele River: Mormyridae (17%), respectively. In Andouwou however, Clariidae dominated Alestidae, Cichlidae and Claroteidae (11%). They are with 18.28%. The family Mormyridae is almost the most followed by Cyprinidae (8%), Clariidae and Mastacembelidae represented in these rivers. These results are consistent with (6%). The rest of the families represent only 3%. In Engondo those found in the Congo basin [5], which showed that River, Mormyridae were the most represented (33%). This Mormyridae were in the lead with 16.2%, followed by family is followed by Cyprinidae and Mastacembelidae Cichlidae 13.1%. The same families were found in the (11%). Other families are less represented (5.6%). Clariidae tributaries of the right bank of the Congo River: in Mambili are the most represented at 20%, followed by the families River [10], in Likouala River [12], in Djiri River [14], in Alima Mormyridae, Claroteidae and Mastacembelidae (15%). The River [11], in the Malebo Pool [2, 16]. other seven families were poorly represented, with 5% each.

Fig 5: Proportional distribution of species richness of families in each river

3.7 Diversity indexes lowest index was observed in the Andouwou River, with 2.97. The diversity indexes make it possible to compare the Species diversity has been found to increase from pole to structure of several populations and to see how they vary in equator [36], high Shannon diversity index values in these four space. Figure 6 illustrates the values of these indexes by rivers are explained by the proximity of the equator. waterways. The Shannon indices of Angouewele River, Angouewele River, Engondo River and Amegni River have Engondo River, Andouwou River and Amegni River were all equitabilities greater than 0.7, the fish populations of these greater than 1. These rivers are very rich and diversified. The waterways are therefore balanced (Figure 6). However, strongest index was found in the Amegni River with 3.96, Andouwou River has an equitabilty of 0.66, this value less followed by that of the Angouewele River which is 3.57. The than 0.7, indicating a slight population imbalance [31].

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Fig 6: Diversity of fish populations of each waterway

Duellman's similarity index allowed us to determine the similarity coefficient between waterways as shown in Figure 7. Strong similarities were observed between Engondo River and Amegni River, Andouwou River and Amegni River, Engondo River and Andouwou River with respectively 66.66%, 60.46% and 55.55%. The similarities between Angouewele River and Engondo River or between Angouewele River and Andouwou River were low (34.61% and 32.14%). The lowest similarity (17.54%) was observed between Angouewele River and Amegni River. These results showed that Angouewele River fish community is different of the three others. The hierarchical classification including the specific richness of four rivers, showed some differences between the data stemming from various sampled stations. The affinity dendrogram of species richness shows different degree of affinity between different waterways (Figure 8). At 60%, three groups can be discriminated, the first group is Angouewele River, the second group is composed of Engodo River and Amegni River. The third group is represented by Fig 7: Similarity of waterways populations R1 = Angouewele Andouwou River. River; R2 = Engondo River; R3 = Andouwou River; R4 = Amegni River

Fig 8: Dendrogram of species richness in the four rivers

4. Conclusion the most represented of Congo basin. The fish population of The inventory of ichthyofauna of the four rivers of Alima these waterways present a very great diversity and its basin of Boundji District, shows a predominance of three distribution is balanced. The presence of required oxygen major orders (Siluriformes, Osteoglossiformes and species such as Pollymyrus sp, Raïamas chrystii, Raïmas Characiformes) and of one family (Mormyridae) which are buchholzi, Mastacembelus sp., proves that waters of these ~ 107 ~ International Journal of Fisheries and Aquatic Studies http://www.fisheriesjournal.com rivers are still of the good quality. This sampling, which Vouidibio J, Diatewa M. Preliminary Data on the completes scares ichthyologic studies carried out in the Alima Ichthyofauna of Djiri River (Affluent of right bank of basin, should be continued on the middle and upper course of Congo River), Int. Res. 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