Here's why:
* Respiration: Like all living organisms, fish need oxygen to survive. They take in oxygen dissolved in the water through their gills.
* Energy Production: During respiration, fish use oxygen to break down food, releasing energy for their bodies.
* Waste Product: A byproduct of this process is carbon dioxide, which is released back into the water through their gills.
Other gases:
While carbon dioxide is the primary gas released, fish may also release small amounts of other gases depending on their metabolism and environment, such as:
* Ammonia: A waste product of protein breakdown, which can be toxic in high concentrations.
* Methane: Produced by some fish in their digestive systems.
* Nitrogen: Can be released as a byproduct of some metabolic processes.
However, these gases are typically released in much smaller quantities than carbon dioxide.