Bitcoin volatility and Zakat?

Salam elikum
Anyone describe how to calculate zakat of Bitcoin and its high volatility , suppose you own Bitcoin and its price went to 65k and now you are holding this asset for one year so its Zakat will be 2.5% and after a week its price went to 40k and you didnt payed the zakat till now so how to calculate ?
Thank you in advance

Wa alaykum salaam,

You will pay according to the amount of bitcoin you had, so if you had 1 BTC, you can give 0.025 as Zakat.

Thank u for response , so it means on that day 0.025 was equal to 2000$ and now its 1000$ so if i pay 1000$ today is it right or not ? so you are not calculating the value of Bitcoin to dollar you are treating it like an asset ? what if not want to sell bitcoin or pay zakat in bitcoin instead i want to pay the zakatable amount in local currency or dollar?