Use a home water-quality test kit to measure the temperature, pH, dissolved oxygen content, ammonia levels, nitrate levels and salinity of water. Adjust these properties as needed. Avoid adjusting water temperature abruptly. Tropical fish have narrow optimum temperature ranges and do not usually tolerate sudden changes in environment. Regulate an airflow rate of 2 liters per hour, per liter of water.
Control airflow with an aerator.
Be sure the fish food also contains required essential amino acids. Feed your fish appropriate amounts based on the amount and type of fish in the aquarium. A general formula is to feed 10g flake food to 50 adult tropical or freshwater fish per month, but check with experts. Avoid overfeeding, which results in poor water quality because of surplus food floating around in the tank. Store food in moisture-resistant containers and place in a cool, dry area.