Standard metabolic rate predicts growth trajectory of juvenile Chinese crucian carp () under changing food availability.

Phenotypic traits vary greatly within populations and can have a significant influence on aspects of performance. The present study aimed to investigate the effects of individual variation in standard metabolic rate (SMR) on growth rate and tolerance to food deprivation in juvenile Chinese crucian carp () under varying levels of food availability. To address this issue, 19 high and 16 low SMR individuals were randomly assigned to a satiation diet for 3 weeks, whereas another 20 high and 16 low SMR individuals were assigned to a restricted diet (approximately 50% of satiation) for the same period.

Interspecific differences in hypoxia-induced gill remodeling in carp.

The gills of many fish, but in particular those of crucian carp (Carassius carassius) and goldfish (Carassius auratus), are capable of extensive remodeling in response to changes in oxygen (O2), temperature, and exercise. In this study, we investigated the interspecific variation in hypoxia-induced gill modeling and hypoxia tolerance in 10 closely related groups of cyprinids (nine species, with two strains of Cyprinus carpio). There was significant variation in hypoxia tolerance, measured as the O2 tension (P(O2)) at which fish lost equilibrium (LOEcrit), among the 10 groups of carp.

Interspecific variation in hypoxia tolerance, swimming performance and plasticity in cyprinids that prefer different habitats.

This study quantified and compared hypoxia tolerance and swim performance among cyprinid fish species from rapid-, slow- and intermediate-flow habitats (four species per habitat) in China. In addition, we explored the effects of short-term acclimation on swim performance, maximum metabolic rate (M(O2,max)) and gill remodelling to detect habitat-associated patterns of plastic response to hypoxia. Indices of hypoxia tolerance included oxygen threshold for loss of equilibrium (LOE50) and aquatic surface respiration (ASR50), and critical oxygen tension for routine metabolic rate (Pcrit).

Habitat-specific locomotor variation among Chinese hook snout carp (Opsariichthys bidens) along a river.

The Wujiang River is a tributary of the upper Yangtze River that shows great variations in its flow regime and habitat condition. Dams have been built along the Wujiang River and have altered the habitats profoundly enough that they may give rise to reproductive isolation. To test whether the swimming performance and morphology of the Chinese hook snout carp (Opsariichthys bidens), varied among habitats and whether the possible differences had a genetic basis, we measured the steady and unsteady swimming performance, external body shape and genetic distance among fish collected from both the main and tributary streams of the upper, middle and lower reaches along the river.