1. Only use medication in your aquarium when you are out of other options. You should use a separate tank to medicate sick fish as some medications can have harmful effects on healthy fish.
2. In larger aquariums, you should put a few scavenger fish in the tank. Scavenger fish will help to clean up left behind food and wastes from the other fish in the aquarium. This is a good eco friendly way to keep your aquarium clean.
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.