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.

Aquatic insects are species of significant importance to water bodies because they serve various purposes including nutrient cycling, vectors of  pathogens and bioindicators of water quality. Analyzing their community structure is a veritable tool in studies of biodiversity and quality of limnetic  ecosystems. Therefore, we investigaTed the health status of a pond in Benin City, Nigeria using insect’s abundance, composition, distribution and physicochemical parameters of the waterbody. Insects were sampled using sweep nets and identified to the species level while water samples were collected and analyzed using in-situ and ex-situ methods to determine the physicochemical properties in three sampling stations. The results of the physicochemical assessment of the water indicated that conditions did not differ widely between sites (P > 0.05) except for total alkalinity, and the recorded values were well within the ambient FMEnv permissible limits for surface water except for dissolved oxygen,turbidity and phosphate. A total of 10 insect taxa, comprising of 103 individuals in 2 orders were recorded in the study and among the orders, Hemiptera comprised of 7 species and Coleoptera comprised of 3 species. Majority of the insect fauna found in this study are typically found in similar water bodies in the tropics. However, the obsereved insect community structure revealed a relatively low taxa richness with a dominance of pollution-resistant species which suggests a moderately polluted condition of the waterbody. Keywords: Aquatic insects, bioindicators, biodiversity, water quality, pond.

The presence of trace metals in the sediment, water, and biota of the Epe lagoon has been recently linked to oil exploration and municipal perturbations around the lagoon. The study was aimed at assessing the concentrations and associated health risks of Fe, Zn, Cu, Ni, Pb, Cd, Cr, Mn, Co and V in the water, sediment, and Gymnarchus niloticus of Epe lagoon and to evaluate the role of the enteric parasite Nilonema gymnarchi in bioaccumulation of the metals in the fish. The temperature, pH, redox potential, conductivity, turbidity, dissolved oxygen (DO), total dissolved solids (TDS), and salinity were determined in-situ using a handheld multi-parameter probe (Horiba Water Checker Model U-10). The concentrations of Fe, Zn, Cu, Ni, Pb, Cd, Cr, Mn, Co, and V were determined in the surface water, bottom sediment, Gymnarchus niloticus, and its enteric parasites, Nilonema gymnarchi in Epe lagoon using the Flame Atomic Absorption Spectrometer (Philips model PU 9100). The bioaccumulation factors and target hazard quotients of the trace metals in the infected and uninfected fish were estimated and compared. The intestinal tissue sections of the infected and uninfected fish were examined using a binocular dissecting microscope (American Optical Corporation, Model 570) using hematoxylin and eosin (H&E) stain. Biochemical markers such as reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and lipid peroxidation (MDA) were determined in the liver of the infected and uninfected fish. The SOD level was higher in the uninfected fish than the infected ones supports the indications deduced from the bioaccumulation analysis. Strong positive correlations between SOD and most of the metals- Fe (0.916), Zn (0.919), Cu (0.896), and Ni (0.917) suggests that the metals may have inflicted more toxicity in the uninfected. The histopathological comparisons made between the uninfected and infected fish showed consistency with the outcomes of other comparisons made in this study. These evidence were marked by tissue alterations in the infected fish ranging from no observed changes to mild alterations, while the uninfected exhibited more severe tissue injuries such as hemorrhagic lesions, severe vascular congestion, edema, the increased connective tissue of the submucosa, and vascular congestion. The condition factors of the infected (0.252) and uninfected (0.268) fish indicated slenderness and unfitness possibly due to environmental stressors such as trace metals. The parasitized fish showing better-coping potentials than the uninfected, coupled with the significant bioaccumulation interferences exhibited by the parasite Nilonema gymnarchi is an indication that the parasites may be a good metal sequestration agent for the fish and can be used to forestall the significant health hazard quotient posed by the current level of iron and the synergy of all metals analyzed in the lagoon.