Surfacing and Asphyxia of Eleven-freshwater Fish under Hypoxia

Abstract

Oxygen saturation of water (So₂, %) at which fish surfaced at the rate of 50% were in the order Zacco temminckii (18.7) and Z. platypus (18.1) >Rhodeus ocellatus ocellatus (17.1) and Gnathopogon elongates elongatus (17.0) >Anguilla japonica (16.3) >Ischikauia steenackeri (13.7) >Cyprinus carpio (11.3) and Sarotherodon nilotica (11.1) >Lepomis macrochirus (8.7) >Pelteobagrus nudiceps (7.9) >Carassius carassius langsdorfii (7) . So₂ (%) at which fish were asphyxiated at the rate of 50% were in the order Z. p. (16.1) >G. e. e. (15.5) >Z. t. (14.1) >C. c. (10.0) >I. s. (9.6) >R. o. o. (9.0) >A. j. (7) >S. n. (6.8) > L. m. (6.0) and P. n. (6.0) >C. c. l. (5) .
In fishes used for the experiment, there were little difference in So₂ between when one fish surfaced and when all fish did (1-5%), between when one fish asphyxiated and when all fish did (1-2%), and between when all fish surfaced and when one fish asphyxiated (0-6%) .