Your 54l tank has dimensions only slightly larger than a 10 gallon. There is not sufficient surface area for two fancy goldfish in that tank. One of them will outgrow it very quickly.
How long have you been keeping fish?
Edit. I read 54 gallons not liters.
Afraid you are over stocked. I have to agree.
Through the constant contradictions, the one consistent rule of thumb is 20G for first goldie and 10G for each additional. That's why I thought I might have room for a couple of small fish.