What are signs of chlorine/chloramine toxicity in fish?

Signs of chlorine or chloramine toxicity in fish are often indicated by abnormal gill coloration and behavior. When fish are exposed to chlorine or chloramines, one of the most notable effects is on their gills, which may become damaged or exhibit signs of stress. This can manifest as pale or tan gills, indicating a lack of oxygenation or a decline in gill health due to chemical irritation or damage.

Pale or tan gills suggest that the fish are unable to efficiently carry out the exchange of gases due to the harmful effects of these substances. Healthy gills should typically appear red or vibrant, reflecting good oxygen transport and blood oxygenation. Therefore, observing gills that are discolored (tan or pale) is a clear indicator of potential poisoning or toxicity.

In light of this, other choices do not align with the expected signs of chlorine or chloramine toxicity. Fish exhibiting bright gill coloration and increased activity are often displaying signs of health or excitement rather than distress. Swimming in circles without distress could indicate a range of behavioral issues, but it is not specific to chlorine toxicity. Additionally, normal feeding habits are not indicative of toxicity, as affected fish may stop feeding altogether due to stress. Thus, the pale or tan coloration of the g