Proper PH for Tropical Fish

For tropical fish, there is no single, proper pH level. Some tropical fish come from freshwater environments, while others come from marine environments; in general, though, most tropical fish will be quite content in water with a pH between 6 and 8.

  1. Maintaining a Steady pH Level

    • Different fish require different pH levels. For example, the ideal pH level for Oscar fish and Betta is between 6.8 and 7.2, but for many types of Cichlids around 8 is recommended. Averaging out the suggested pH levels will be an effective means of establishing which pH is best for your tank. However, the most important thing about the pH level of your tropical fish tank is that you should keep it steady. As long as the pH is between 6.5 and 8, your fish should be fine; but short-term fluctuations in the pH level will upset the body chemistry of the fish and lead to health problems.

      Keeping the pH level stable is especially important when changing your tank water--which should be done regularly to ensure a clean living environment for the fish. Before changing the water, measure the current pH level in the tank and then adjust the new water to match that level. This adjustment must be done before putting the fish into the new water, or you risk shocking their systems. Performing frequent partial water changes, in addition to proper cleaning, vacuuming of the gravel and maintaining good aeration help keep water pH stable.

    Adjusting pH Levels

    • If you do need to change the pH level, your fish can adapt provided the change is gradual--change it in small increments.

      At an aquarium supply store, buy a test kit that contains chemicals referred to as "pH up" and "pH down." Measure your aquarium's current pH level, and compare it against what you consider to be the ideal pH level for the fish in your tank (keeping in mind that you should not change the pH too much). Add "pH up" to raise your tank's pH; add "pH down" to lower it. If you prefer to adjust the pH level by gentler, non-chemical means, you could add pieces of wood to your tank to lower the pH, or add a seashell or a coral skeleton to raise the pH. These methods take time and will not quickly produce noticeable effects.

      If your water contains buffers, it will be more difficult to adjust the pH level. Buffers act to keep pH levels stable, so this will require a careful mix of buffers and pH adjusters.

    Testing pH Levels

    • Test pH levels with a tank testing kit from an aquarium supply store. Use a sample of your aquarium's water from about 8 to 12 inches below the water line, and be sure to carefully follow the kit instructions.