Ecology of some species of catfishSynodontis (Pisces: Mochocidae) in the Kpong Headpond in Ghana

Ofori-Danson, Patrick K.

doi:10.1007/bf00001157

Cited by 17 publications

(13 citation statements)

References 4 publications

(2 reference statements)

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“…Lauzanne, 1988;Ofori-Danson, 1992). However, whether or not the Synodontis, especially S. koensis actively searches for scales or ingest them at random is a question that remains to be investigated.…”

Section: Discussionmentioning

confidence: 99%

Preliminary data on the feeding habits of the endemic speciesSynodontis koensisPellegrin, 1933 (Siluriformes, Mochokidae) in a West African River (Sassandra River Basin, Côte d’Ivoire)

Yao

Kouamé

Ouattara

et al. 2010

Knowl. Managt. Aquatic Ecosyst.

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Key-words:Synodontis koensis, endemic species, feeding habit, Sassandra River, Côte d'Ivoire In the implementation of programs for protection and management of ichthyofauna, endemic species should have high priority in the conservation measures. Their fishery should be based on intimate knowledge of their ecology and biology. Feeding habits of the endemic Mochokid Synodontis koensis were assessed in the Sassandra River (Côte d'Ivoire) in relation to the study zone, the specimen sex and size, and the season. Of the 303 stomachs examined, 49 were empty (16%). The fluctuation of the vacuity index indicated that S. koensis feeds more at night. The diet consisted mainly of plant detritus and chironomid larvae. The statistical analysis of the feeding according to the study zones, the sex of fish and the seasons does not show any significant difference between regimes, whereas significant ontogenic shifts in diet were observed. Dans la mise en oeuvre de programmes pour la protection et la gestion de l'ichtyofaune, les espèces endémiques doivent faire l'objet d'une attention particulière. Leur exploitation doit se faire sur la base d'une bonne connaissance de leurs éco-logie et biologie. Les habitudes alimentaires de Synodontis koensis, espèce endémique du fleuve Sassandra (Côte d'Ivoire), ont été étudiées pour la première fois en fonction de la zone d'étude, du sexe et de la taille des spécimens et de la saison. Sur 303 estomacs examinés, 49 étaient vides (16 %). La variation de l'indice de vacuité indique que S. koensis se nourrit surtout la nuit. Elle consomme principalement des débris végétaux et des larves de Chironomidae. Le régime alimentaire ne présente de variation statistiquement significative ni en fonction de la zone d'étude, du sexe et ni des saisons. À l'inverse, il est fonction de la taille des individus. RÉSUMÉ

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Section: Discussionmentioning

confidence: 99%

Preliminary data on the feeding habits of the endemic speciesSynodontis koensisPellegrin, 1933 (Siluriformes, Mochokidae) in a West African River (Sassandra River Basin, Côte d’Ivoire)

Yao

Kouamé

Ouattara

et al. 2010

Knowl. Managt. Aquatic Ecosyst.

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“…Several workers have studied the reproductive biology of S. schall in some other African water bodies such as breeding season (Halim and Guma'a, 1989;Lalèyè et al, 2006), size at first maturity (Willoughby, 1979;Albaret, 1982, Ofori-Danson, 1992 and fecundity (Nawar, 1959;Halim and Guma'a, 1989;Ofori-Danson, 1992). However, no published work is available on the reproductive biology of S. schall in Lake Chamo.…”

Section: Introductionmentioning

confidence: 99%

Length-weight relationship, breeding season, sex ratio, maturity and fecundity of the Nile catfish <i>Synodontis schall</i> (Bloch and Schneider, 1801) (Pisces: Mochokidae) in Lake Chamo, Ethiopia

Dadebo¹

2016

Eth J Sci & Technol

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Length-weight relationship and some aspects of reproductive biology of the Nile catfish Synodontis schall (Bloch and Schneider, 1801) in Lake Chamo, Ethiopia were studied from fish sampled in each month during January to December 2010. The relationship between fork length (FL) and total weight of males (TW = 0.020FL 3.207 , R 2 = 0.965, n = 277), females (TW = 0.020FL 3.248 , R 2 = 0.976, n = 407) and the sexes combined (TW = 0.020FL 3.240 , R 2 = 971, n = 684) were curvilinear and statistically significant (ANOVA, P<0.05). The proportion of breeding fish was high between May and September, during which time 46.8% -72.0% of the males and 41.3% -77.9% of the females had ripe gonads. Thus, the months with high proportions of breeding fish were considered as the breeding season of the fish. More number of females was caught in all size classes but sex ratios were significantly different from 1:1 in size classes 30.0-34.9 cm FL and 35.0-39.9 cm FL. The overall male to female sex ratio of 1:1.39 was also significantly different (χ 2 = 24.71, P<0.001) from the theoretical ratio of 1:1. Size at first maturity of males was 23.1 cm FL while that of females was 26.4 cm FL. Fecundity ranged from 3,500-54,089 eggs with a mean of 21,017 eggs. The mean relative fecundity of S. schall was 76.1 eggs g -1 of body weight. The average number of eggs g -1 of ovary (preserved wet weight) ranged from 983 to 3,797 with a mean of 1,847 eggs g -1 . The relationships between fecundity and fork length and fecundity and total weight were curvilinear while the relationship between fecundity and ovary weight was linear.

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“…The spawning sites are unknown, but it is fairly certain that they do not spawn in the pelagic zone as pelagic eggs, embryos and larvae were not found. Studies of other Synodontis species in Africa have indicated that breeding periods are associated with the rainy season (Lock 1974, Halim & Guma'a 1989, Ofori-Danson 1992 and that spawning takes place in shallow water. Lock (1974) observed that S. schall in L. Turkana spawned in the lake in less than 1 m of water after influx of freshwater during the rainy season, and in rivers during the same period.…”

Section: Discussionmentioning

confidence: 98%

Distribution and breeding biology of offshore pelagic cyprinids and catfish in Lake Malawi/Niassa

Thompson¹,

Allison²,

Ngatunga³

1996

Environ Biol Fish

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Lake MalawiNiassa is a permanently stratified lake, consisting of an oxygenated layer of 230 m depth that overlies an anoxic zone that extends to the lake bottom at a maximum depth of over 700 m. Some fish are found throughout the oxygenated zone of the offshore waters, and lead a pelagic existence, although many of the species form part of the demersal community in shallower waters where the lake-bed is oxygenated. This paper reports on the distribution of cyprinids and catfish at six offshore locations, sampled with a mid-water trawl and gillnets, along the north-south axis of the lake. These two groups formed, respectively, 5% and 13% of the offshore fish biomass in the trawl catches. The offshore cyprinids comprised the small lake-spawning Engraulicypris sardella, the only species to have pelagic larvae, and the larger river-spawning Opsaridium microcephalum and 0. microlepis. These cyprinids occurred mainly in the upper 100 m of the water column. The biomass of both larvae and adults of E. sardella showed considerable fluctuations over the two years of study. The spawning site of E. sardella remains a mystery, but is no longer believed to be in the offshore pelagic zone. The most abundant catfish was the mochokid Synodontis njassae, that exhibited diurnal movements from just above the oxic-anoxic boundary layer during the day to the surface layers at night. The clariid catfish of the genus Bathyclarias were caught infrequently offshore, but owing to their large size, they could form a significant part of the biomass. Their abundance was difficult to quantify, as it was believed that the majority are active in the nearsurface layers and were under-sampled by the trawl and gillnets. Information on some aspects of the breeding biology is included in the paper, although our knowledge in this area is very incomplete.

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Ecology of some species of catfishSynodontis (Pisces: Mochocidae) in the Kpong Headpond in Ghana

Cited by 17 publications

References 4 publications

Preliminary data on the feeding habits of the endemic speciesSynodontis koensisPellegrin, 1933 (Siluriformes, Mochokidae) in a West African River (Sassandra River Basin, Côte d’Ivoire)

Preliminary data on the feeding habits of the endemic speciesSynodontis koensisPellegrin, 1933 (Siluriformes, Mochokidae) in a West African River (Sassandra River Basin, Côte d’Ivoire)

Length-weight relationship, breeding season, sex ratio, maturity and fecundity of the Nile catfish <i>Synodontis schall</i> (Bloch and Schneider, 1801) (Pisces: Mochokidae) in Lake Chamo, Ethiopia

Distribution and breeding biology of offshore pelagic cyprinids and catfish in Lake Malawi/Niassa

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