Long-Duration Carbon Dioxide Anesthesia of Fish Using Ultra Fine (Nano-Scale) Bubbles.
BACKGROUND
We investigated whether adding ultrafine (nano-scale) oxygen-carrying bubbles to water concurrently with dissolved carbon-dioxide (CO2) could result in safe, long-duration anesthesia for fish.


RESULTS
To confirm the lethal effects of CO2 alone, fishes were anesthetized with dissolved CO2 in 20°C seawater. Within 30 minutes, all fishes, regardless of species, died suddenly due to CO2-induced narcosis, even when the water was saturated with oxygen. Death was attributed to respiration failure caused by hypoxemia. When ultrafine oxygen-carrying bubbles were supplied along with dissolved CO2, five chicken grunts were able to remain anesthetized for 22 hours and awoke normally within 2-3 hours after cessation of anesthesia.


CONCLUSIONS
The high internal pressures and oxygen levels of the ultrafine bubbles enabled efficient oxygen diffusion across the branchia and permitted the organismal oxygen demands of individual anesthetized fish to be met. Thus, we demonstrated a method for safe, long-duration carbon dioxide anesthesia in living fish under normal water temperatures.
Division of Nutritional Science, Graduate School of Human Health Science, University of Nagasaki, Nagasaki, 851-2195, Japan.
Kenji
K
Kugino
Division of Nutritional Science, Graduate School of Human Health Science, University of Nagasaki, Nagasaki, 851-2195, Japan.
Shizuka
S
Tamaru
Department of Health and Nutrition Science, Faculty of Health and Social Welfare Science, Nishikyushu University, Saga, 842-0015, Japan.
Yuko
Y
Hisatomi
Institute of Marine Sciences and Technologies, Marine Biotechnology Inc, Fukuoka, 811-3501, Japan.
Tadashi
T
Sakaguchi
D000768:Anesthesia, General / Q000379:methods*; D019162:Anesthetics, Combined / Q000008:administration & dosage*; D000818:Animals; D002245:Carbon Dioxide / Q000008:administration & dosage*; D005399:Fishes / Q000502:physiology*; D000860:Hypoxia / Q000139:chemically induced; D045423:Microbubbles; D036103:Nanotechnology / Q000379:methods*; D010100:Oxygen / Q000008:administration & dosage*; D012119:Respiration
D019162:Anesthetics, Combined; D002245:Carbon Dioxide; D010100:Oxygen