if you have big amounts to convert i think you consult a accountant.
Regardless of the amount, if the law on your country has clear provisions regarding the taxation of cryptocurrencies in general, then you are subject to comply regardless of the amount. But if there are no laws pertaining to cryptocurrencies and taxes, then you are not liable of anything. There is no crime when there is no law punishing it. Assuming that there is, please do not attempt to evade or to create any shenanigans since it might create a stigma that would further put cryptocurrencies in a tight spot which can ultimately affect everyone.