How about hooking up a flood and drain tank (aquaponics) with your fish tank with redworms in the media? Although my aquaponic tanks are raft tanks and I don't use redworms, I've been told the redworms flourish in the media and reproduce.
It's a win win as if you do it right. You won't even have to do water changes in your fish tank as your plants will consume the nitrates and your media will do your biological and mechanical filtration. And you can produce fresh produce.
A few on here can verify if you can produce enough redworms and how much media you would need.
If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.
