Obviously, if you have Bitcoins and you live in a country where they are taxed, you must pay them. You must get in contact with the person who makes your taxes for you and ask them what you need to do. If that person doesn't know either, find yourself another because cryptocurrencies will be more and more common in our lives, and people who don't know about them and do that sort of job should be considered inefficient at their job.

You must seek the advice of an accountant especially if the legal frame concerning cryptocurrencies is not very clear in your country, which is true for a lot of countries right now.