Ammonia and nitrite accumulated in intensive aquaculture are toxic to aquatic animals and disrupt their physiological functions. The both chemicals can be converted into nitrate by nitrifying bacteria. However, the bacteria grow extremely slowly and are susceptible to many factors such as dissolved oxygen, organic matter, temperature and pH. This study, we compared nitrification efficiency when the nitrifying bacteria were cultured on different attached media. The results expressed that zeolite and activated carbon were better than others as attached media. Both zeolite and activated carbon can absorb ammonia-N. Additionally, zeolite with ammonium ion exchange property offered a high concentration of ammonium and pH to keep ammonia-oxidizing bacteria, and subsequently improved nitrification and decreased ammonia-N.