KUMASI, Ghana — A new study from the Kwame Nkrumah University of Science and Technology (KNUST) has revealed critical insights into the breathing behavior of African catfish.
Researchers say this could enhance fish farming practices across the continent.
The research, published in Environmental Biology of Fishes, shows that the African catfish (Clarias gariepinus) can triple its air-breathing rate when exposed to high levels of carbon dioxide in water, underscoring the species’ remarkable adaptability to shifting aquatic environments.
Known for its unique ability to breathe both dissolved oxygen and atmospheric air, the African catfish surfaces periodically to breathe directly from the air.
Researchers found that when carbon dioxide concentrations reached 40 milligrams per liter, the fish significantly increased its breathing frequency.
“When oxygen levels drop, catfish rely more on air-breathing,” said Dr. Kwasi Adu Obirikorang, lead scientist on the study. “Farmers can reduce stress and mortality by ensuring proper aeration, especially in densely stocked ponds.”
The study also revealed that air-breathing increased sharply under low oxygen conditions—more than doubling at moderate and severe lows compared to normal levels.
Temperature shifts further influenced the behavior. As water temperatures rose, breathing rates increased until a critical threshold was reached, after which they began to decline.
In stratified water columns where temperature layers vary, catfish adjusted their breathing based on the temperature of each layer.
Dr. Obirikorang warned that higher carbon dioxide levels may lead to frequent breathing and energy loss. He recommends regular water exchange and effective filtration systems to maintain balanced gas levels.
He also urged farmers to monitor seasonal temperature changes to prevent overheating, which could push fish beyond their thermal tolerance.
“By applying these insights, fish farmers can improve growth rates, reduce stress-related losses, and create better conditions for sustainable catfish farming,” Obirikorang said.