The effect of digested sludge on the common carp, Cyprinus carpio L
Wong, M.H.; Luk, K.C.; Liu, W.K.; Kwan, S.H.
Acta Anatomica 103(2): 130-133
1979
ISSN/ISBN: 0001-5180 PMID: 419924 Document Number: 153378
The effects of sewage sludge on the survival of the common carp C. carpio were investigated. When the concentrations of the sludge used for rearing carp exceeded 0.6%, the fish died within 42 days, whereas those reared in 0.2% sludge remained alive and healthy during the trial period. The body and the gills of the dead fish were covered by a veil-like film which looked like coagulated mucus and was formed by the heavy metal ions from the sludge reacting with some constituents of the mucus secreted by the gill. The histopathological symptoms of the various organs further demonstrated that internal injury in liver and kidney was an important feature of the intoxicants and external damage, especially the particles observed around the gills. The optimum concentration of sludge to any species of fish should be determined by testing a series of concentrations before using it as a supplementary fish feed or fish pond fertilizer.