Freshwater fishes are faced with increasing threats due to intensification of agriculture. This study evaluated the haematological and genotoxic effects of exposure of the African Catfish, Clarias gariepinus to sublethal concentrations of commonly used pesticides in agricultural settings. The evaluated pesticides were abamectin, carbofuran, chlorpyrifos, cypermethrin, deltamethrin, dichlorvos, dimethoate, fipronil, lambda-cyhalothrin and paraquat. The fishes were initially exposed singly to the pesticides for 96 h periods to determine their LC 50 , followed by exposure to sublethal concentrations (1/100 th 96 h LC 50 ) over a 21 d period. In all cases, a control experiment with catfishes kept in dechlorinated municipal water was monitored simultaneously. The 96 h LC 50 values was found to vary widely from 2.043 μgL -1 (Lambda-cyhalothrin) to 10284.288 μgL -1 (Paraquat). Significant differences (P < 0.05) were observed between mean haematological parameters-WBC, RBC, HGB, HCT, MCH and MCHC in the exposed and control catfishes. More so, micronucleus and nuclear abnormalities occurred at significantly higher proportions in pesticide exposed catfishes. Holistic cradle to grave approach as well as fate analysis is required to mitigate the potential harmful effects of pesticides to fresh water fishes.

This study was done to evaluate the drying performance, efficiency, and effectiveness of five different types of improved low-cost solar driers in terms of moisture loss from two tropical African fish species Clarias gariepinus (African sharp tooth catfish) and Oreochromis niloticus (Nile tilapia) and testing the organoleptic characteristics of the dried samples. The driers used were made from plastic, aluminum, glass, glass with black igneous stone, and mosquito net, with traditional direct open-sun drying as a control. A significant (P < 0.05) decrease in weight resulting from moisture loss in the two fish species was observed in all the driers, with the highest reduction occurring in the glass drier containing black stone. The rate of weight loss was faster in the first 4 days of drying with black stone-inserted glass drier showing the fastest drying rate with a constant weight in C. gariepinus attained on the 11th day and in O. niloticus on the eighth day. The slowest drier was plastic where a constant weight of the species were recorded on and 13th day and 11th day, respectively. Volunteers were used to assess the organoleptic characteristics of the dried samples and they showed lowest acceptability for the open-sun drying, while samples from the glass drier containing black stone had the highest acceptability in terms of the taste, flavor, appearance, texture, odor, palatability, and shelf-life. The low-cost solar driers were effective found in removing water from the fish resulting in significant loss of weight and moisture. The highest drying time, efficient performance, drying effectiveness, and high acceptability of the organoleptic parameters of the dried products from the black stone-inserted glass drier were due to the ability of the glass and the black stone to retain, transmit, and radiate heat to the fish sample all the time (day and night). These low-cost driers are simple to construct, materials for its construction readily available, easy to maintain and operate, hygienic in use, reliable, effective, occupies less area, dry products faster with increased shelf-life, save man-hour, user-friendly, use renewable energy, protect the drying samples from filthiness, wetness, and invasion by pests, insects, and microbes, with well-dried, high-quality, and better preserved final products. The adoption and use any of these low-cost solar driers by artisanal fishermen and general household in sub-Saharan Africa will not only help in reducing post catch losses, but also ensure food safety and security as there is abundant solar energy in these sub-Saharan African tropical countries for the operation of the driers.

No abstract

Qualitative performance and economic analysis of five low cost solar driers were evaluated at the Zoology and Physics Laboratories of the University of Ilorin, Ilorin, Nigeria. The solar driers were constructed from mosquito net, plastic, aluminum and glass with black stone inserted in it. The driers were found to be better than the other driers because they are cheap, reliable, safe to use, easy to repair, well insulated, and cost effective. The solar driers are compact, efficient with drying of fish with lowest moisture content achieved within a few days and the dried products of good quality, with long shelf life, highly acceptable to consumers. The driers save man-hour, money, use renewable energy, with no operational or maintenance costs. The driers have a long life span, with net income to fisher folks very high and the payback time for the driers very low.  The adoption of the driers will contribute to the economy of rural populace in the developing countries where there is no electricity and the challenges of deforestation are becoming prominent. The improved low cost solar driers will ensure food safety and security and assist in combating climate change resulting from burning of wood and fossil fuel.

Qualitative performance and economic analysis of five low cost solar driers were evaluated at the Zoology and Physics Laboratories of the University of Ilorin, Ilorin, Nigeria. The solar driers were constructed from mosquito net, plastic, aluminum and glass with black stone inserted in it. The driers were found to be better than the other driers because they are cheap, reliable, safe to use, easy to repair, well insulated, and cost effective. The solar driers are compact, efficient with drying of fish with lowest moisture content achieved within a few days and the dried products of good quality, with long shelf life, highly acceptable to consumers. The driers save man-hour, money, use renewable energy, with no operational or maintenance costs. The driers have a long life span, with net income to fisher folks very high and the payback time for the driers very low.  The adoption of the driers will contribute to the economy of rural populace in the developing countries where there is no electricity and the challenges of deforestation are becoming prominent. The improved low cost solar driers will ensure food safety and security and assist in combating climate change resulting from burning of wood and fossil fuel.