Light and scanning electron microscopy of the effects of Macrogyrodactylus congolensis (Prudhoe, 1957) on the skin of the African sharptooth catfish Clarias gariepinus (Burchell, 1822). Issue 4 (1st February 2022)

• Record Type: Journal Article
• Authors: Maduenyane, Mpho; Dos Santos, Quinton Marco; Avenant‐Oldewage, Annemariè
• Is Part Of: Journal of fish diseases. Volume 45:Issue 4(2022)
• Page Start: 595
• Page End: 602
• Publication Date: 2022-02-01
• Subjects: aquaculture -- epidermal histopathology -- fish parasite -- Gyrodactylidae -- Monogenea; Fishes -- Diseases -- Periodicals; 639.3
• DOI: 10.1111/jfd.13584
• Languages: English
• ISSNs: 0140-7775

Abstract

Abstract: Clarias gariepinus (Burchell, 1822) is one of the two most actively cultured freshwater fish in Africa and therefore, economically important. Specimens of this species were purchased from a fish farm near Hartbeespoort Dam (North West, South Africa) and introduced into the tanks of the research aquarium in the Department of Zoology at the University of Johannesburg. However, the skin of these fish was infected with Macrogyrodactylus congolensis (Prudhoe, 1957), which proliferated profusely in the favourable conditions of the aquarium, posing a potential threat to its host. The current study was aimed at examining the pathology caused by M. congolensis on the skin of C. gariepinus . Species identification of the parasite was confirmed using light microscopy (LM), scanning electron microscopy (SEM) and DNA barcoding of the internal transcribed spacer region. Examination of the pathology was studied using LM of haematoxylin and eosin–stained sections (epoxy embedded) and SEM of parasites attached to the hosts' skin. Infected skin exhibited excessive mucus production, corroborated by an increased number of mucus cells alongside proliferated and abnormally enlarged club cells, resulting in varying thickness of the epidermal layer. At the site of attachment, the basement membrane detached from the dermis. Hamulus points and marginal hooks of the parasite pierce through the hosts' skin resulting in tearing. Epidermal cells and melanin granules were observed in the intestinal lumen of the parasite. Melanin granules were absorbed by the parasite's intestinal epithelium confirming that the parasite feeds on host skin tissue.