A 200-gallon fish tank generally costs between $500 and $1,000. The price may vary depending on factors such as the tank's brand, material, and additional accessories included. It's important to consider the quality and durability of the tank as well as any special features it may have. Additionally, purchasing additional items like a stand, filter, heater, and lighting will add to the overall cost. Researching different brands and comparing prices from multiple retailers can help you find the best deal. It's also worth checking for any seasonal sales or discounts that may be available. Remember, investing in a high-quality tank is crucial for the well-being of your fish and enjoyment of your aquarium hobby.