Not sure what country you’re in, but if it’s the United States, the rates on all but the 20- and 30-year bonds are less than 1%, and even the long bonds are all under 2%.
I certainly wouldn’t consider those usurious interest rates. In fact, if anything I’d be more worried about the real interest rate on the bonds (after accounting for inflation) being less than 0. If that were the case, then in real terms you would be getting paid
less than you gave them, which would
definitely not be usury.
By the way, I’m not sure what the portfolio is, or what your time horizon is, but just FYI, if it’s a bond
fund, it’s going to lose value if interest rates increase. (Which they almost have to, given than they’re basically 0 now, unless you’re expecting negative nominal rates.) I mention that only because you said you’re 18, and I think a lot of people your age probably don’t understand how bond funds work.