1. Some people go by the ìinch of fish, gallon of water rule when deciding on how large of an aquarium to buy. This is a completely false and bad method to go by, you should always check your individual fish's tank requirements.
2. 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.
3. When adding plants to the aquarium, be sure to check the lighting needs. Try to find plants that will fit the pre-existing lighting conditions of your aquarium. You should avoid plants that require much more light than the fish in your aquarium.