Bond funds do not guarantee principal and income. Bond fund is an investment tool, and its income is related to the fluctuation of bond market. The portfolio of bond funds usually consists of various types of bonds, including government bonds, corporate bonds and other fixed-income securities. The price and yield of these bonds will fluctuate with the change of market interest rate.

Although bond funds are generally regarded as relatively stable investment tools, they can't guarantee no loss of principal or fixed income. The income of bond funds is affected by the fluctuation of bond prices and the credit risk of bond issuers. If the bond market fluctuates greatly or the bond issuer defaults, the net value of bond funds may fall and investors may suffer losses.

Therefore, investing in bond funds needs to pay attention to market risk and credit risk, and make choices according to their own risk tolerance and investment objectives. If you want to protect the capital and income, you may need to consider other more stable investment tools, such as bank deposits or capital-guaranteed wealth management products.