Ryukin goldfish require a 30-gallon tank for the first fish, plus 10–15 gallons for each additional fish, with high-quality filtration to handle their high waste output. They thrive in 65–75°F (\(18-24^{\circ }\text{C}\)) water with a pH of 6.5–7.5. Feed them sinking pellets, flakes, and frozen foods to prevent swim bladder issues. Maintain pristine water quality with regular, frequent water changes.