Why Goldfish are the most popular pet fish

Goldfish are popular pet fish because they can be trained like other pets. For example when the pet owner will enter the room, the gold fish in the bowl are immediately detecting that the pet owner has come to the room, and are frantically asking for food . This is in contrast to other types of fish like Koi, Fighter Betta Fish which are largely passive and do not react when there is any movement or noise in the room where the fish bowl is located
The goldfish are also easy to keep fish as they as they remain alive for a relatively long period of time without much maintenance or care, in contrast to other fish like Koi, Guppies which are dying quite quickly
So though expensive at Rs 150 a pair, gold fish are highly recommended as pet fish