Koi Fish in a 55 Gallon tank?

Rehome them, if a pond is not option then keeping them in not an option. They will get way bigger than 1'. Koi get Huge and need a 1,000+ Gallon Pond. And your tank is big enough for the ryukins, Cray fish, and telescope. But you will need to rehome the koi, common, and comet goldfish. These aren't called pond fish for no reason, Common/Comet Goldfish will eventually need 55G for ONE!

You should start looking for a new home for the koi, or return it. he will groe maybe half an inch to one inch a month or more, he needs a new home before he gets stunted. The comman and commet Should also have a bigger tank, the 55 is very full with the 3 fancys. The other problem, the commanand commet will be much faster and more agile then the fancies, especially the telescope!, and they will get much more of the food. the fancies might not starve, but the commans can get bloated.

Its possible that you can add one ore fancy goldfish after you rehome the commans and koi.

No, you can't keep a koi long-term in a 55-gallon tank.

They don't grow to be 1 foot long, they grow to be 2 to 4 feet long.

You'd best re-home your fish with someone who has a large, deep pond.

Koi need to be in a pond as they grow way too big for tanks. Also, your tank is overpopulated. Comet and common goldfish need much more than a 55 gallon.

Right now, no problem, but adult size is more like 2 ft+. Thinks 1,000 gal pond to house adult Koi. But like I said, this isn't a problem right now, so don't panic. But you need to rehome them in the near future.