also if you can tell me how big is too big
koi indoors will not grow much in a year if your doing this for profit there will be no profit at all. Can you raise koi indoors yes there are many poeple keeping koi indoors to avoid all the problems encountered by outside pond predators, weathers, heavy rains.
Down side indoors slow growth color could fade.
sample video in a aquarium
kOi keeper & goldfish keeper
Raising Koi For Profit
Koi grown in an indoor aquarium will rarely look as colorful or healthy as pond grown fish. This is because the sunlight will enhance color development and a diet of bugs, worms, live plants and algae will supplement their fish pellets and help them grow big and strong.
Stick to tropical fish if you want to raise fish that the fish stores will buy. I raised zebra danios, gold barbs and dwarf gouramis when I was young. Find a fish that is in short supply but in great demand and then learn all you can about it and it’s breeding habits. If it’s a new color variety of an easy to breed fish, that would be a good choice but be sure you don’t waste time on color injected fish, hybrids or genetic mutations with pot bellies or curved spines.
Or you could try raising cherry shrimp. They breed fast, grow fast and are one of the hardiest freshwater shrimp to raise. They are small so you don’t need a huge tank and they eat a variety of fish foods. Many pet stores have trouble buying cherry shrimp from wholesalers because they don’t ship well so they will be happy to buy your home grown shrimp as long as they are healthy and have good color.
Ask your local fish store for other fish that they want to buy locally but be sure they know you are just a beginner at this. You need to start with something fairly easy if you want to succeed. Join a local fish club so you can learn about the fish that do best in your local water. You can get great breeding stock this way or tips on raising live food.
sure why not?
Koy get big (3ft+)
Thanks for the answers everyone xx