1. Catfish sometimes require freshwater as juveniles and then as they get old they will need a more brackish environment. Make sure you read up on your catfish to learn what its needs will be when it gets older.
2. Clownfish do not always need to be with a sea anemone. Clownfish use anemoneís in the wild and they are not completely necessary in the home aquarium. If you insist on owning an anemone, you need to have plenty of experience to take care of it as they can be difficult to manage.
3. It is a good idea to keep carbon on hand in case of emergencies. Carbon can be used to soak up anything harmful that may be introduced into your aquarium. So keeping an emergency stock can be a life saver.