* Carbon Dioxide is a Waste Product: Fish, like all animals, produce carbon dioxide as a byproduct of respiration. They need to get rid of it, not take it in.
* Oxygen is Essential: Fish, like all animals, require oxygen for cellular respiration. This is the process that converts food into energy.
* Gill Function: Fish use their gills to extract oxygen from the water and expel carbon dioxide.
* High CO2 Levels are Harmful: While a small amount of CO2 dissolves in water naturally, high levels of CO2 can make water acidic, which can be harmful to fish and other aquatic life.
In summary: Fish need oxygen to survive and they produce carbon dioxide as a waste product. They need to expel CO2, not take it in.