Goldfish will generally eat it all up. Definitely try zuchinini an cucumbers. Romaineis the only lettuce ive heard, and i wouldnt do spinach as it contains a buttload of minerals. I never heard o using citrus. If it isnt eaten in half an hour I would take it out.this would be the cheapest way to get veggies to ur goldies- Try getting a small one to ten gallon tank to leave outside, and get a bit of duckweed (an aquatic plant). It grows like crazy. Grab a handful every day and put it in ur goldie tank. They should eat that right up - and if they dont they will later. Dont introduce it into a tank without goldfish tho.