What should the oxygen level be for tropical fish?

Tropical fish require well-oxygenated water to breathe and thrive. The optimal oxygen level for most tropical fish species should be between 5 and 8 milligrams per liter (mg/L). Some fish, such as tetras and barbs, may require oxygen levels slightly higher than 8 mg/L, while others, like loaches and catfish, can tolerate slightly lower oxygen levels, around 4-5 mg/L. Oxygen levels below 4 mg/L are considered too low and can cause stress, disease, and even death in tropical fish. To maintain adequate oxygen levels, aquariums should be equipped with adequate filtration and aeration systems, such as air pumps with airstones or powerheads to agitate the water surface. Adding live plants to the aquarium will also help in oxygenating the water and creating a more natural environment for the fish. Regular monitoring of oxygen levels through test kits or oxygen meters is recommended to ensure they stay within the appropriate range for tropical fish species.