How to grow duckweed faster than a goldfish can eat?

just throw a tupperware container with some water and duckweed in a windowsill. free food.

You really shouldn't grow food inside the tank because goldfish don't know when to stop eating and some die from over eating. It is very common for an owner to think, oh my fish still wants to eat let me feed him some more, but that is very unhealthy and will kill the fish. I suggest buying fish food or growing it in a different container.

In response to the first question, just grow A Lot and then before he can eat it all it will have already have started growing back :D

Hope this helped. Btw I would really really really appreciate 10 points

How To Grow Duckweed

The growth rate of Duckweed is directly tied to the brightness of the available light. It requires lots of light.

Get separate tanks, or containers. You can grow the duck weed in large Rubbermaid containers.

Transplant as needed, or just feed as needed.