Here's why:
* Temperature: Angelfish are tropical fish, requiring water temperatures between 78-82 degrees Fahrenheit (25-28 degrees Celsius). Pond water temperatures fluctuate greatly depending on the season and weather, making it impossible to maintain a suitable temperature for angelfish.
* Water Chemistry: Angelfish prefer soft, slightly acidic water conditions. Ponds often have varying water chemistry due to natural elements like rain, runoff, and decaying organic matter.
* Predators: Ponds are home to a variety of predators like snakes, birds, and larger fish that could easily prey on angelfish.
* Space and Environment: Angelfish need a spacious environment with plenty of hiding places and open areas for swimming. Most ponds lack the specific plants, decor, and shelter that angelfish require.
If you are interested in keeping angelfish, you will need a heated aquarium with proper filtration, water parameters, and a suitable environment.