Studies on the Offensive-Odor Fish of the Nagara River. VII. Median Tolerance Limit Test of the Offensive-Odor Substances

Abstract

The three components, volatile fatty acids, aromatic hydrocarbons, and phenol, found as the main substances responsible for the unpleasant odor in fish meat, can also act as a toxic substance. In order to know the toxicity of these substances to fish and to reveal the correlation between water quality and toxicity in the area where fish with bad odor lived, median tolerance limit (TLm) tests were made with a carp (Cyprinus carpio L.). The values of TLm found for acetic acid were 69 ppm for 24 hr and 49 ppm for 48 hr, those for propionic acid were 96 ppm for 24 hr and 73 ppm for 48 hr, those for butyric acid were 85 ppm for 24 hr and 65 ppm for 48 hr, and those for valeric acid were 92 ppm for 24 hr and 72 ppm for 48 hr, and those for phenol were 3.6 ppm for 24 hr and 1.7 ppm for 48 hr. In aromatic hydrocarbons, the fish were alive even in 1500 ppm of any of them and TLm values could not be measured. In the TLm tests with a mixture of these substances, concentrations of these substances in the water area in which fish with unpleasant odor lived were several tenths to several hundredths of the experimental TLm values, since the fish can live in such waters. These substances are considered to act as an inducer and the fish living in such polluted waters for a long period of time acquire unpleasant odor. © 1976, The Pharmaceutical Society of Japan. All rights reserved.