North American Veterinary Licensing Examination (NAVLE) Aquatics Practice Exam

Chlorine toxicity in fish can cause severe stress or even death, as chlorine is a potent irritant and can damage gills, leading to respiratory distress. The effective treatment for chlorine toxicity involves the use of sodium thiosulfate or activated carbon. Sodium thiosulfate is a chemical that acts as a reducing agent, neutralizing free chlorine in the water and converting it into non-toxic forms. When added to the water, it effectively mitigates the harmful effects of chlorine, allowing the fish to recover and thrive. Activated carbon also plays a crucial role in filtering out chlorine. It can adsorb chlorine and other harmful substances from the water, thus improving the overall water quality and providing a safer environment for the fish. In contrast, adding more fish to the tank does not address the chlorine toxicity and can actually exacerbate stress among the existing fish due to increased competition for resources and the burden of toxins. Increasing the water temperature may increase the metabolism of fish but does not address the root cause of chlorine toxicity. Lowering the pH of the water does not detoxify chlorine and could further impact fish health negatively, as sudden changes in pH stress fish. Using sodium thiosulfate or activated carbon provides a direct pathway