Article info.

ABSTRACT

Received 27 Dec 2017
Revised 05 Mar 2018

Accepted 30 Mar 2018

This study is aimed to evaluate the effects of different carbon dioxide (CO₂) levels on acid-base regulation and growth performance of basa catfish (Pangasius bocourti). The study included two experiments, (1) effect of different CO₂ levels (1%, 2%, 3%) on fish blood physiological parameters,and (2) effect of CO₂ levels on fish growth performance. In the first experiment, the experimental setup consisted of a big tank (1 m³) that recirculated water to 4 smaller tanks (200 L) with 45 fish in each. The water partial pressure of carbon dioxide (pCO₂) was controlled with an Oxyguard Pacific box coupled with a G10 ps CO₂ probe and a K01svpld pH probe (Oxyguard International A/S, Farum, Denmark). The blood samples were collected at 0, 1, 6, 24, 48, 72, 96 and 168 hrs. after equilibration to investigate pH_e, pCO_2, [HCO₃^-] and [Cl^-] in plasma. The grow-out experiment was set up for 60 days and fish was weighed at the day 0, 30 and 60. The results showed that, after 1 hr. of CO₂ exposure, pH_e wassignificantly decreased (7.51±0.01 in control fish and 7.28±0.02 in the fish exposed to CO₂ 3%, this parameter was recovered after 6 hrs. pCO₂ and [HCO₃^-] increased at all CO₂ exposed groups. After 168 hrs., pCO₂ and [HCO₃^-] in plasma of 3% CO₂ exposed fish were significantly increased and reached the values of 20.7±1.35 mmHg and 22.2±1.16 mM, respectively; those pCO₂ and [HCO₃^-] values were 2.7 and 3.2-fold as high as the values of control fish. [Cl^-] concentration in plasma of fish in 2% and 3% CO₂ treatments were significantly decreased after 48 hrs. of CO₂ exposure in comparison with control treatment (p<0.05). Besides, weight gain, daily weight gain and specific growth rate were significantly decreased, while feed conversion ratio increased with the increase of CO₂ concentrations (p<0.05). In conclusion, carbon dioxide was found to have significantly effects on acid-base regulation and growth performance of fish. Increasing of carbon dioxide in aquaculture systems should be regulated.

Keywords

Basa catfish, acid-base regulation, CO₂, growth, Pangasius bocourti

Cited as: Ha, N.T.K., Bieu, N.T.X., Phuong, N.T. and Huong, D.T.T., 2018. Effect of CO₂ on acid-base regulation and growth performance of basa catfish (Pangasius bocourti). Can Tho University Journal of Science. 54(2): 18-26.