Abstract

A series of experiments were conducted to determine changes in water quality and mortality rates of channel catfish fingerlings under conditions simulating transport. Data gathered to date indicates that accumulation of carbon dioxide in the water was the factor responsible for the initial mortalities which occurred. Unionized ammonia was not believed to be a factor contributing to mortalities.

Several experiments were conducted to determine the efficacy of ion exchange resins in reducing rates of mortality. A mixed bed ion exchange resin shows promise as an absorbent of significant amounts of both carbon dioxide and ammonia.

Notes

Various stressors such as high CO₂ and ammonia levels, oxygen depletion and crowding occur in fish during transport. It is thought that crowding alters hormone levels in the fish causing increased steroid levels and thus decreased resistance to disease.

Severe crowding caused CO₂ accumulation, 0₂ depletion and death. In uncrowded conditions there was only CO₂ accumulation, however, death also occurred. Stress due to CO₂ accumulation was evidenced by rapid gill movements, increased peripheral blood flow and running at the side of the container.

Ammonia build-up can be reduced through use of Clinoptilolite. This is a type of clay which absorbs ammonia and is used in sewage plants for this purpose. Clinoptilolite (or "Kitty Litter") can be placed in the container with the fish. It should be used for freshwater fish only.

To combat CO₂ buildup there is a type of resin which can be used. Anesthetics can also be used to decrease the basal metabolic rate of the fish and thus delay buildup of toxic substances. Salt and bacteriostats such as Methylene Blue or Acriflavine can be used as prophylactics.