not every commodity is convenient to use as money. For example, take your fish: it will quickly deteriorate, it is difficult to divide into equivalent parts, besides, depending on the exchange rate, you may have to carry an absurd amount of fish with you to make all the necessary purchases. On the other hand, silver coins also have their internal problems if they are traded in very large or very small quantities. In this Bitkoyn undoubtedly surpasses them, and therefore it is much more valuable. It's just the best money.