1. Goldfish can live incredibly long periods of up to 25 years. You should plan accordingly when you purchase a goldfish.
2. You need to have some healthy natural bacteria to process the wastes and chemicals in your aquarium. This will take around 4 weeks to grow naturally, but you can purchase products to speed up the process.
3. Angelfish are normally very peaceful fish, in times of breeding they can get aggressive. It is a good idea to only keep one pair of mating angelfish in the same aquarium, as more of them can lead to infighting.