Tolerance of carp Cyprinus carpio and black bullhead Ictalurus melas to Gas-supersaturated water under lotic and lentic conditions

Abstract Most evaluations of the effects of gas-supersaturated water on aquatic organisms have been conducted under test conditions which did not represent lotic (flowing) situations in the field. Thus, fish were not forced to swim. Testing under conditions that forced swimming would be more representative of riverine environments. We evaluated tolerance to gas-supersaturated water of common carp Cyprinus carpio and black bullhead Ictalurus melas from Italy under lotic conditions (i.e. forced swimming) and compared the results with those we previously obtained under non-forced swimming (lentic) conditions. Black bullhead contracted gas bubble disease more quickly under lotic than under lentic conditions. Below 133% total gas pressure (TGP) carp were also more susceptible in lotic rather than lentic conditions. However, above 133% TGP carp were more susceptible to gas-supersaturated water under lentic conditions.