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The Loskop Dam is the most polluted impoundment in the Olifants River, because it receives pollutants from the entire mine-dominated upper catchment. However, histopathology of fish inhabiting this polluted dam is scantly explored. The current study aimed to investigate the histopathology of the gills and liver of Labeo rosae from Loskop Dam. Alkaline pH was observed throughout the study with most metal concentrations exceeding the water quality guideline for aquatic ecosystems. Regressive changes were the most prominent lesions for both organs with gills showing relatively more pathologies than the liver. Epithelial lifting was 100% prevalent during both seasons in the gills whereas a significant expansion of lipofuscin-laden melanomacrophages (MMCs) showed 100% prevalence in the liver. Gills were significantly different in their prevalence of histopathology between the two seasons, which was not the case for liver. The histopathology recorded in this study shows that the health of L. rosae at Loskop Dam was compromised. Given the exacerbating pollution level in the upper Olifants River, these findings serve as a warning to conservation authorities and emphasise the necessity for regular monitoring of fish health at Loskop Dam to assess pollution levels using fish health as a sensitive indicator to altering pollution levels. [ABSTRACT FROM AUTHOR]

The effect of seasonal changes and ecological aspects of Afrodiplozoon polycotyleus (Paperna, 1973) collected on Labeobarbus marequensis (Smith, 1841), Enteromius trimaculatus (Peters, 1852) and Enteromius radiatus (Peters, 1853) was investigated from January to October 2008. Fish were collected at the Nwanedi-Luphephe dams, Limpopo River System, South Africa using gill, cast and seine nets and electrofishing gear. Enteromius radiatus and E. trimaculatus were the most infested compared with L. marequensis. Seasonal changes had an influence on the intensity of A. polycotyleus, with infestation rates higher in spring, summer and autumn. The adults predominantly infected the medial region of the second gill arch, whereas diporpae were mainly found on the first gill. Neither sex nor water quality changes had an influence on the intensity of the parasite. The health condition of the hosts was not affected by the parasite. The different infestation rates of the parasite between the species could be attributed to host characteristics, behaviour and habitat preferences. The selection of a particular gill/region could be attributed to space for attachment organs and food supply, as well as flow and velocity of the water over the gills. The occurrence of A. polycotyleus on E. radiatus constitutes a new host record. [ABSTRACT FROM AUTHOR]