Abstract
We analyzed the relationship between water quality and freshwater fish in major first-grade river systems in northern Kyushu, Japan. The number of fish species preferring flowing water showed a significant negative correlation with BOD, while that of fish species preferring standing water showed no correlation with BOD. The results of receiver operating characteristic curve analysis indicated statistical relationships between the presence of several fish species and some environmental factors including BOD. The comparison between the periods 2001-2010 and 1991-2000 indicated that the number of fish species increased with improvement in river water quality.
