Alkalinity, hardness, pH, ammonia and dissolved oxygen are important parts of water quality. Dissolved oxygen is the most important part of water quality to understand. Dissolved Oxygen Catfish, like all other animals and plants, require oxygen. Oxygen is necessary to use their food for growth and activity. Catfish can live only in water.
Fish remove oxygen from the water with their gills.
The more oxygen there is in the water, the easier it is for them to breathe. Nitrogen and oxygen are the most common. Air has plenty of oxygen in it. Water has much less oxygen than air. High quality water has 20,000 times less oxygen than our air.