Tosai Japanese Koi are first-year young koi, typically small, fast-growing and very active, making them an exciting stage for development of colour and pattern. They are peaceful pond fish but more delicate than older koi, so they do best in clean, well-filtered ponds with very stable water parameters. A minimum pond volume of around 2,000–3,000 litres is recommended for a small group, with good aeration and regular maintenance as they grow quickly and produce increasing waste. Tosai koi thrive on a high-quality, growth-focused diet and should ideally be kept with similarly sized koi to prevent bullying and ensure they get their fair share of food.
