Koi

Finally, Toplist has another unusual fish: the koi. Koi fish are carp that have been bred to look a specific way. While they are technically affordable, they can also cost more than a million dollars. Their cost is determined by a variety of factors. These elements include their bloodline and skin color. The right combination of these is priceless in Japan. Koi is one of the few domesticated fish. They are ornamental fish that are mostly used to decorate tanks and ponds.

Koi is the name given to the Amur carp, but it is also used to describe the colors of koi. A koi fish can be white, orange, black, red, or gold in color. There are numerous koi species. Consider dog breeds as a good koi comparison. All dog breeds are dogs, but each breed is worth a different amount of money.

Koi are mostly peaceful freshwater fish. They will eat anything a human will eat (as will most carp). They are not your typical aquarium fish, but for the right person, they are an excellent addition and can be quite valuable. After all, each aquarium owner has their own preferences.

They are auctioned off once a year in Japan, with prices ranging from $100 to the aforementioned $1 million USD. They also don't take up much space.

A large number of koi can coexist in a small space. Each one only requires 29 gallons of water to succeed. However, because they are predators, it is not recommended that they be stored with other fish unless absolutely necessary.

Price: $100 - $1 million