Design and Construction of Degassing Units for Catfish Hatcheries

eries, water in egg-hatching or fry-rearing tanks may have a condition called “gas supersaturation” that is harmful to fish. Gas supersaturation means that the water contains more gas at a certain air (barometric) pressure and water temperature than would normally occur if the water was allowed to come to equilibrium with the atmosphere. Fish living in such waters may develop a stressful or lethal condition called gas bubble trauma. Gas supersaturation can occur frequently in hatcheries, and small fish confined in shallow tanks are especially susceptible to gas bubble trauma. Because the diffusion of excess gas out of water can be slow, water often must be treated before it is used in a hatchery. Gas supersaturation problems may be difficult to diagnose, but are easily remedied with simple, inexpensive equipment such as the packed-column aerator described here.