title: Fasting goldfish, Carassius auratus, and common carp, Cyprinus carpio, use different metabolic strategies when swimming.
abstract: Fish need to balance their energy use between digestion and other activities, and different metabolic compromises can be pursued. We examined the effects of fasting (7 days) on metabolic strategies in goldfish and common carp at different swimming levels. Fasting had no significant effect on swimming performance (U(crit)) of either species. Feeding and swimming profoundly elevated total ammonia (T(amm)) excretion in both species. In fed goldfish, this resulted in increased ammonia quotients (AQ), and additionally plasma and tissue ammonia levels increased with swimming reflecting the importance of protein contribution for aerobic metabolism. In carp, AQ did not change since oxygen consumption (MO(2)) and T(amm) excretion followed the same trend. Plasma ammonia did not increase with swimming suggesting a balance between production and excretion rate except for fasted carp at U(crit). While both species relied on anaerobic metabolism during exhaustive swimming, carp also showed increased lactate levels during routine swimming. Fasting almost completely depleted glycogen stores in carp, but not in goldfish. Both species used liver protein for basal metabolism during fasting and muscle lipid during swimming. In goldfish, feeding metabolism was sacrificed to support swimming metabolism with similar MO(2) and U(crit) between fasted and fed fish, whereas in common carp feeding increased MO(2) at U(crit) to sustain feeding and swimming independently.
authors.affiliation: Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp, Belgium. honjung@umt.edu.my
authors.forename: Hon Jung
authors.initials: HJ
authors.lastname: Liew
authors.forename: Amit Kumar
authors.initials: AK
authors.lastname: Sinha
authors.forename: Nathalie
authors.initials: N
authors.lastname: Mauro
authors.forename: Marjan
authors.initials: M
authors.lastname: Diricx
authors.forename: Ronny
authors.initials: R
authors.lastname: Blust
authors.forename: Gudrun
authors.initials: G
authors.lastname: De Boeck
mesh_terms: D000641:Ammonia / Q000097:blood / Q000378:metabolism; D000818:Animals; D002347:Carps / Q000378:metabolism; D004734:Energy Metabolism; D029941:Fish Proteins / Q000378:metabolism; D005508:Food Deprivation; D006003:Glycogen / Q000378:metabolism; D006054:Goldfish / Q000378:metabolism*; D019344:Lactic Acid / Q000097:blood; D050356:Lipid Metabolism; D008099:Liver / Q000033:anatomy & histology / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism; D009929:Organ Size; D010101:Oxygen Consumption; D005082:Physical Exertion; D013550:Swimming
chemical_list: D029941:Fish Proteins; D009124:Muscle Proteins; D019344:Lactic Acid; D000641:Ammonia; D006003:Glycogen