How big is a fully grown panda oranda fancy goldfish?
They can and often will get to be about 10 inches. Could be more, could be less depending on a number of factors. Goldfish are best kept with at least 15 gallons per fish. 40 Liters is just about 10 gallons, which is not quite enough for just that one fish, let alone any other fish you might keep with him. They make a lot of waste, and a small tank will cause waste poisoning issues and / or stunt growth. The minnows shouldn’t get very big, but ideally aren’t kept with the goldfish. If they aren’t bothering him though, I guess it’s not an issue. Consider a 30 gallon (120L) tank and a canister filter as an upgrade.
