Money you invest in a Registered Retirement Savings Plan (RRSP) grows tax deferred until you withdraw it.
You receive a tax deduction (so you pay less income tax) for any funds you contribute to the plan.
Any growth on the investment within the RRSP is taxed as income.
Any losses on the investment within the RRSP are not able to be claimed as a capital loss against your RRSP.
The Canada Revenue Agency (CRA) views it as a loss which cannot be deducted.