摘要：In the context of responsible handling and good welfare practices, fish must be anesthetized to lessen the effects of the stressors to the fish. There are a number of commercially available anesthetics that are being marketed, but some of these products are not easily accessed by fish farmers in some aquaculture sites particularly those in the rural areas or these chemicals are expensive for the small-scale fish farmers to purchase. The use of sodium bicarbonate, commonly known as baking soda, was tested as an alternative and inexpensive anesthetic during fish handling and transport using red tilapia hybrids as a model fish species. Red tilapia hybrid juveniles with weights ranging 1–4.5 g were exposed to two concentrations of sodium bicarbonate at 50 and 100 g l−1 in both fresh- and brackishwater (20 ppt) conditions. Regardless of the dose of the anesthetic, juvenile red tilapias that were reared in brackishwater took a longer time to be fully anesthetized than those reared in freshwater. In both rearing environments, the concentration of the anesthetic has an effect on the time to induce anesthesia of the fish. In addition, the time to full recovery of the fish was not significantly different in both rearing environments and was not affected by the dose of the anesthetic. A concentration of at least 50 g l−1 is recommended for anaesthetizing red tilapia hybrid juveniles in both rearing environments at water temperatures in the range of 26–29 °C.
