GROWTH PROMOTING EFFECT OF SUSTAINED SWIMMING IN COMMON CARP Cyprinus carpio

Jyotsna Shrivastava*, Božidar Rašković, Ronny Blust, Gudrun De Boeck
 
Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Antwerp, Belgium
Jyotsna.Shrivastava@uantwerpen.be
 

Induced swimming has the potential to improve the growth and feed conversion efficiency of fish. However, these premises are not explored extensively for the aquaculture fish species. Therefore, the present study was conducted to reveal the effect of swimming exercise on promoting the growth rate and augmenting physiological capacity of common carp (Cyprinus carpio). This species is widely distributed worldwide and extensively used for aquaculture and is therefore of great commercial and ecological importance.

The trials were conducted with common carp juveniles to determine whether constant swimming at different speeds has an influence on growth, metabolic and physiological indices endpoints. The trial lasted for 28 days and was undertaken in three large (1600 L) recirculating aquaculture system called raceways flume (with flow created by an impeller driven by an electric motor). Three groups of 100 fish (mean weight of 4.87 g) were assigned to a constant swimming regime at different speeds: 0 (control), 1.5 and 2.5 body lengths per second (BL/s). Additionally, once in a week, 8 randomly selected fish per group were transferred to Blazka-type respirometers (3.9 L) for evaluation of swimming performance. The results showed a significant increase in the body weight gain for the group swum constantly at 2.5 BL/s compared to both control (0.0 BL/s) and 1.5 BL/s group at the end of week 1, 3 and 4 (Fig. 1). Contrary to the weight gain, there were no significant differences between the groups in critical swimming speed (Ucrit) and oxygen consumption rate; although there was a trend of increasing oxygen consumption and decreasing Ucrit in each group during the course of the trial.

Energy budget (hepatic and muscular) showed no difference between experimental groups, however following the week 4 there was a significant increment for protein content in liver of 2.5 BL/s group. Quantitative real-time PCR (qPCR) based expression level of a set of growth genes revealed clear regulatory roles in relation to swimming speeds. The mRNA transcript levels of growth hormone receptor as well as insulin-like growth factor were significantly up-regulated in hepatic tissue of 1.5 and 2.5 BL/s groups.  Overall, our study revealed a growth promoting effect of sustained swimming in common carp, and provides a prospective of implementing swimming as a tool to increase fish production in commercial aquaculture system.