Can goldfish live in a cast iron water butt?

Goldfish are not suited for living in a cast iron water butt or any other type of water container that is not designed for keeping fish. Cast iron water butts are not suitable for keeping fish because they are not designed to maintain a stable water temperature, provide adequate filtration, or provide enough space for the fish to swim and hide. Additionally, the metal can leach harmful toxins into the water, which can be fatal to the fish.

Goldfish are a species of carp that are native to East Asia. They are coldwater fish, meaning that they prefer water temperatures between 65-72°F (18-22°C). In a water butt, the water can fluctuate outside the optimal range and fish can either get cold and stressed or be prone to bacterial infection.

Finally, cast iron water butts often do not provide enough space for goldfish to move around and hide, which can lead to stress, disease, and even death.

For the best chance at success in keeping goldfish, they should be kept in an appropriately-sized aquarium with a filter, heater, and other necessary equipment to keep the water clean, oxygenated, and at a suitable temperature.