Mass death of fish and worms are often observed in Japan recently.
(cf. More than 1,000 bonitos found dead in Wakayama western Japan
More than 10,000 earthworms found dead in a parking lot of 250m2 North Japan
Mass of whip ray found going upstream of river in Chiba
Thousand small fish found dead in Kasumi river Tokyo)
Numerous loaches were found dead in Akita prefecture.
It was in a drainage channel near Tsuchizaki port, Akita city. Fishery products center of Akita prefecture analyzed the dead bodies to comment It’s unlikely that they died of disease or deficiency of oxygen. There might have been a rapid change of environment.” on 8/17/2012.
Citizens nearby the drainage channel reported the environment department of the city government that loaches were dead. The city staff found loaches (2~10cm) dead for about 1km in the channel.
The number is not known but Japanese mitten crab, Oikawa minnow and Ugui minnow were found dead too.
The drainage channel is 1~2m wide, 20~70cm deep. Household wastewater and factory drainage come to the channel too, but from the research of Akita city, dissolved oxygen and pH were in the normal range.
The environment department was reported that the loaches were dead since before 8/15/2012, they are to continue researching.