fantails keep pooing

Question
For the last 3week or so my 4fantails 2large 2small just keep pooing. I feed them once a day, the water and filter get cleaned weekly. In general they look ok all swimming around. They live in a large tank around a 60 one. They eat flakes and occasionally they have live blood worm my other fish are ok.What can i do.

Answer
Michelle,
I want to make sure I understand. You have 2 large and 2 small fantail goldfish. What size tank are they in and what other fish are with them? What are your ammonia, nitrite and nitrate levels. What does the poo look like? Is it white and stringy, or does it have color? This is very important for me to be able to help you. Please, get back to me with the answers so I can help you better.