Fish is a very perishable foodstuff whose preservation requires a continuous cold chain. The study aims to evaluate the effect of the break in cold chain on the bacteriological quality of Scomber scombrus (Atlantic mackerel) and Trachurus trachurus (Horse mackerel). Thus, data were collected from June to December 2016 in South Benin. A total of 120 fish were divided in control (cold chain integrity) and experimental (3h, 6h and 12h of break in cold chain) batches in order to determine the microorganism loads by cold chain break duration. Total Mesophilic Aerobic Flora (TMAF) and Clostridium perfringens loads were significantly higher in chilled fish samples than in frozen fish (p<0.001). However, no significant difference was observed between the control and the experimental batches whatever the preservation method and the cold chain break duration (p>0.05) for the TMAF. No Clostridium perfringens was counted for the freezing. Similarly, Staphylococcus aureus were not counted, except in the refrigerated batch for 3 hours of cold chain break. The TMAF and Clostridium perfringens loads increased according to cold chain break duration. For the FMAT, the highest load was observed at 12 hours of break in cold chain. In the majority of cases, Enterobacterium load was higher in the experimental batches compared to control batches. No samples revealed the presence of total coliforms, fecal coliforms, Salmonella and Escherichia coli. The rigorous cold chain keeping throughout the preservation until consumption significantly prevents the proliferation of fish contamination flora.

With an aim of reducing the cost of aquacoles feed, we carried out substitution partial of an imported raw material: the fish meal (FP) by under local product: flour of ground worm (FV). The experiment undertaken on the youthful ones of Tilapia (Oreochromis niloticus), monosexe male, having an initial average weight of 6.24 ± 0.39g (average weight ± ES), consists in testing 2 iso-proteinic and iso-energy diets containing the same rates of the various ingredients. During 45 days of experiment the final average weights reached values ranging between 27.66± 4.06g and 42.46 ± 10.53g according to treatments'. The best growths and food transformations were obtained with treatments T2 and T3 (specific growth rates: respective TCS = 7.25±0.18 and 7.60 ± 0.39% and food conversion rate: respective TCA = 1.30 ± 0.94 and 1.28 ±0.76), while with food T1 one obtained a TCS of 5.90 ±0.15% and a TCA of 1.81±0.17. Ultimately, and in comparison with the analyses of economic profitability, the results obtained, showed that the incorporation of this by-product (FV) ata rate of 15% involves a profit of 29.1 % on the financial expenses related to the station of the food without causing injury with the growth of fish. Thus, substitution partial of the fish meal by the flour of ground worm is possible and more advantageous when the fish are nourished with the fresh ground worms. It allows, moreover, the reduction of the loads related to the food of Tilapia and the valorization of this neglected by-product.

The main objective of this synthesis is the state of knowledge, potential, inadequacies and interest of assembling two bioindicators, specifically zooplankton organisms and aquatic macroinvertebrates. The analysis of published articles, master theses, doctoral theses, technical information documents, manuals and identification guides and other documents relating to the study of the two groups of organisms in the tropical region was made. According to this analysis, aquatic zooplankton and macroinvertebrate organisms are extremely diverse and have potential sentinel species (pollu-sensitive and pollu-tolerant). These two groups of biondicators, by their diversity of taxonomic and functional forms, their variable life span, their wide distribution in running water and their different trophic positions, are complementary and thus constitute excellent tools for assessing the state of Health of hydrosystems. Their association would make it possible to account for the perfect state of health on all the sectors of the aquatic ecosystems. This article gives an overview of what is known about commonly used bioindicators, reveals some shortcomings of the work carried out and finally proposes guidelines for future studies.