1. Goldfish can live incredibly long periods of up to 25 years. You should plan accordingly when you purchase a goldfish.
2. Do not overfeed the fish in your aquarium. Keep your feeding times at scheduled intervals to avoid overfeeding. If you are just starting your feeding routine, start out small and increase the amounts you put in on how much your fish eat.
3. You should feed your fish a variety of food and not just flake foods. Mix it up with fresher foods from their regular diet. Giving them more a varied diet will increase the general health of your fish.