Key-words:spawning activities, Chromidotilapia guntheri, Ivorian coastal streamsThe reproductive activities of a small Cichlid Chromidotilapia guntheri were investigated from July 2003 to March 2005 in four coastal rivers (Ehania, Eholié, Noé and Soumié), in the southeast of Côte d'Ivoire. Trends in gonadosomatic indices and reproductive stages of development suggested that C. guntheri is a multiple (fractional) spawner and breeds all year round with little fluctuation in spawning intensity. However, spawning activities were more intensive in August and September. The estimated mean standard length at first maturity did not differ significantly between rivers. It was, in the overall population, 85.53 mm SL for males and 100.13 mm SL for females. In general, the sex ratio differed from 1:1 with the predominance of the males in rivers, standard length classes, seasons and the entire population. Absolute fecundity (F) varied from a minimum of 70 to a maximum of 470 eggs. The range of variation in the relative fecundity was from 3066 to 9135 eggs per kilogram of fish in the total population. Fecundity did not differ extensively between rivers. The absolute fecundity relations to fish standard length (SL) and eviscerated weight (We) were best described in the whole population by the following equations: F = 0.00069 × SL 2.72 and F = 2.54 × We 1.15 , respectively. Moreover, there was no relationship between absolute fecundity and oocyte diameter. a varié de 70 à 470 ovocytes dans toute la population et n'a présenté aucune différence significative entre les rivières. Les relations fécondité absolue (F)-longueur standard (LS) et fécondité absolue-poids éviscéré (We) ont été mieux décrites respectivement par les équations suivantes : F = 0,00069 × LS 2,72 et F = 2,54 × We 1,15 . En outre, il n'est apparu aucune relation entre la fécondité absolue et les diamètres ovocytaires.

Micralestes eburneensis Daget 1965, an endemic characin fish of Ivory Coast / Liberia is assessed as Near Threatened due to its restricted range. In addition, there is strong fishing pressure, habitat loss and aquatic pollution from clandestine gold mining in the Cavally River bed.Moreover, given the development and intensification of mining activities in the study area, it is to be expected that the population of the endemic species will continue to decline. The strong anthropogenic pressure in this region on the Cavally hydrosystem and its environment must be taken into account for a future update of M. eburneensis conservation status.There is an immediate need for developing protection and management actions for this fish species.

The feeding habit of Chromidotilapia guntheri was investigated in seven hydrosystems of Ivory Coast. The contents of 156 non-empty stomachs were examined from specimens caught in the rivers Soumié , Eholié , Noé , Ehania and Banco, the Bea rill and the Kpoda lake. Diets composition, feeding strategy and trophic niche width were analyzed among hydrosystems. Stomach content analysis indicated that C. guntheri feeds preferentially on plants and insects debris and secondarily, it consumed insects' larvae, nymphs and adults in all habitats. This species would be an omnivorous with a detritivorous tendency. As feeding strategy, it practices a generalist strategy even if some individuals displayed specialization intentions on insects at different stages of metamorphosis. Investigations on ontogenetic shift revealed that juveniles and adults of C. guntheri consume substantially the same types of prey with varying amounts depending on the size of the fish. However there is a significant decrease in the proportions of gastropods and oligochaetes ingested when growing.

Two experiments were conducted consecutively in triplicates to evaluate and compare the impact of different feeds on survival rate and growth performances of Oreochromis niloticus larvae during both the heat treatment for thermal masculinization and the subsequent juvenile stage. A commercial feed containing fishmeal with 32.38% crude protein (CFA) and an experimental feed with 25.48% crude protein (EFB) where fishmeal was entirely replaced by soybean meal were tested. In the first experiment, larvae of about 4 days post-hatch were reared for 21 days at a temperature of 36°C and the second has consisted in testing at ambient temperature the performances of these feeds on the previous fry for 70-72 days. Fish were fed four times a day ad libitum.Results showed that there were no significant differences between growth performances (survival rate, final body weight, daily weight gain and specific growth rate) of larvae bred in hot water and nourished with feed containing fishmeal (CFA) or feed containing soybean (EFB) as protein source. However, better results were obtained with control batches bred at ambient temperature and fed with feed CFA or EFB. Postlarval rearing of previously heated fry showed that feed containing fishmeal has similar growth performances as feed containing soybean. Then, soybean meal can replace successfully fish-meal in diet of larvae during heating treatment for masculinization and also for the postlarval rearing of fry.

Diversity and Degree of organization of the ichthyological population of two tributaries of the Bandama River in the Marahoue region located in the center-west of Côte d'Ivoire were studied. Indeed, the two tributaries of the Bandama River that are Marahoue and White Bandama Rivers draining this region are subject to numerous disturbances, the main one being gold panning. Data collection was conducted from September 2019 to November 2020 from experimental and artisanal fisheries. The mesh sizes of the gillnets used for the experimental fishery varied from 10 to 40 mm mesh size. The results showed a dominance of the order Siluriformes represented by 6 families and 18 species in the Marahoue River against 4 families and 13 species in the White Bandama River. Also, the Shannon Index (H') values obtained in the White Bandama River (H' fluctuates from 2.26 to 2.33 bits/ind) are lower than those obtained in the River Marahoue (H' fluctuates from 3.02 to 3.14 bits/ind). Our results also highlighted the equitability. This index appeared relatively high in the Marahoue River (E varies from 0.77 to 0.80) compared to the White Bandama River (E varies from 0.5 to 0.57). Consequently, the Marahoue River appears to be more stable and has a good degree of organization of the ichthyological population compared to the White Bandama River.