You can also raise your own ducked weed or spirulina to feed yourself and your fish but it is difficult trying to balance a completely closed system where it is zero input so I highly recomand waiting till you own a couple years of experience in your belt before trying to grow your own fish food.
You can also grow your own duckweed or spirulina to feed yourself and your fish, but it is difficult trying to balance a completely closed system where there is zero input so I highly recommend waiting until you have a couple of years of experience under your belt before trying to grow your own fish food.