This is false. In Canada, 50% of your capital gains are considered tax-free and 50% of the gain is taxable. The tax rate on that 50% is whatever your marginal tax rate is.

So if you have capital gains of $100,000 in one year, you don't pay any taxes on $50,000 at all. For the remaining $50,000 the tax you pay is [ 15% / 20.5% / 26% / 29% / 33% ] depending upon which bracket you're in.