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Table 4 Morphological and behavioural observations of fingerling of O. niloticus in low pH and control

From: Tolerance level of different life stages of Nile tilapia Oreochromis niloticus (Linnaeus, 1758) to low pH and acidified waters

Observations pH 3 pH 4 pH 5 pH 6 Control
Morphological None as mortality was recorded Very dark body colouration, slimy mucous secretions on the gills and body surface; peeling and skin erosion, bleeding from the dorsal fins and bending of the caudal fin, some fins became disintegrated Very dark body colouration, slimy mucous secretions on the gills and body surface; peeling and skin erosion, bleeding from the dorsal fins and bending of the caudal fin, some fins became disintegrated Normal body colouration except some few dark patches, no morphological abnormalities observed. Normal body colouration, no morphological abnormalities seen
Behavioural None as mortality was recorded Lethargy, they were confined to the bottom of the tanks and only moved when agitated with the movement being in one direction, feeding impaired
Swimming velocity decreased
Lethargy, they were confined to the bottom of the tanks and only moved when agitated with the movement being in one direction, feeding impaired Swimming velocity decreased Movement not impaired, they were seen on the surface of tanks, no abnormal behavioural activities observed Normal movement and behavioural responses observed