How do I Convert From Freshwater to Brackish Water?

Brackish water is part freshwater and part saltwater. Some species of fish are born in freshwater but prefer brackish water as they get older. This requires the aquarium to be slowly converted from freshwater to brackish water.

  1. Salinity

    • Salinity is measured based on how much salt is dissolved in the tank. Brackish water is quickly achieved by adding 2 tbsp. of marine salt for every 10 gallons. The salt should be completely dissolved in a separate dish before being added to the tank.

    Density

    • Density is essentially how heavy the water is, and it is the easiest way to make sure the brackish water is perfect for the fish. Test the water using a floating hydrometer. Brackish water should measure between 1.000 and 1.025.

    Considerations

    • Many pet stores sell brackish water fish in freshwater tanks. These include mollies, silver dollars and violet gobies. Slowly convert them from freshwater to brackish water by adding small amounts of salt regularly until proper salinity and density is reached.