An Estimation of the Minimum Level of Dissolved Oxygen in Water Required for Normal Life of Fish

Abstract

It is important to estimate the minimum level of dissolved oxygen in water required for normal life (provisionally named “the critical level for normal life”) of fish, for estimation of the carrying capacity of a fish pond or a fish farm and estimation of required volume of fresh water inflowing per unit time. It was found that the minimum level of dissolved oxygen in water required for maintenance of the oxygen content of arterial blood at the normal level (provisionally named “the critical level for normal value of arterial oxygen”) almost coincided with “the critical level for normal life” estimated from culture, in rainbow trout, carp and eel. Therefore, “the critical level for normal value of arterial oxygen” is considered to be able to be used as a convenient and reliable substitute for “the critical level for normal life”. © 1971, The Japanese Society of Fisheries Science. All rights reserved.