Blue gold fish ill

[r2danny2]

I noticed the last couple of days my blue gold fish (not sure the official name) has been a bit slow and while cleaning the tank it stayed on its side for ages. It's clearly not well. What's the best thing to do ? Shall I remove it from the tank so it doesn't make the others ill ? I have a tropical warm tank with 6 different types of gold fish. Any help would be great Have attached a pic of when it was well.

[Maxw47]

Well first off, that is a platy, not a goldfish... How big is your tank? Are your other fish platies or goldfish? What are the parameters?

[r2danny2]

That's the thing. I just inherited the tank and fish. I know nothing about looking after fish or what fish they even are. I know nothing about the tank size or anything. Sorry. I'm
A total
Novice

[DragonFish71]

One of these might help you figure out the tank size:
Chart of Tank Sizes
FantasyReef Calculators

These will help you get started:
Fish-in Cycling: Step over into the dark side - Aquarium Advice
Guide to Starting a Freshwater Aquarium - Aquarium Advice