Abstract:
Pansteatitis has been identified in wild populations
of sharptooth catfish, Clarias gariepinus (Burchell),
and Nile crocodiles, Crocodylus niloticus Laurenti,
inhabiting the same waters in the Olifants River
Gorge in the Kruger National Park, South Africa.
Mesenteric and pectoral fat tissue was investigated
microscopically and by fatty acid analysis in
healthy and pansteatitis-affected catfish from both
captive and wild populations. Variation in fatty
acid composition between pectoral and mesenteric
fat was noted. Composition of mesenteric fat differed
between fish from various localities as a
result of differences in diet. Pansteatitis in the
captive population, resulting from ingestion of
high amounts of dietary oxidized fat, reflected
higher levels of unsaturated fatty acids within the
mesenteric fat. Mesenteric fat of pansteatitisaffected
wild catfish was characterized by an
increase in moisture content, a decrease in fat content
and a decrease in stearic and linoleic acids.
The n-3 to n-6 fatty acid ratio of mesenteric fat
was higher in pansteatitis-affected wild catfish than
in healthy catfish from the same locality, reflecting
higher polyunsaturated fat intake by pansteatitisaffected
fish. The possible role of alien, invasive,phytoplankton-feeding silver carp, Hypophthalmichthys
molitrix (Valenciennes), in the aetiology
of pansteatitis in both catfish and crocodiles in
the Olifants Gorge is discussed.
