Hi and welcome. It is great you are here to find out what is going on with your fish. AS mentioned above most of us land here because our fish aren't doing well.
While waiting for you to give us a little more info I will go over a couple things for you.
Water quality is everything to a gf. They are very messy and produce alot of waste that can make them sick or kill them. That is why it is recommended that 1 fancy gf be in 10 gals of water each. A common gf needs 20 gals each. Hopefully you were aware of this.
Next, testing the water each day while it is cycling is a must. A cycling tank can easily kill a fish.
Tests you will need are ammonia, nitrites, nitrates and PH. Also tests for hardness is also recommended.
Are you familar with cycling a tank? If not we can help you there too.
GF are very prone to digestive problems, especially the fancy kind. Swim bladder disease is common. You can help to prevent SBD by soaking the gf food and making sure it sinks instead of float on top for them to eat it.
They also like a variety of veggies and fruit in their diet.
GF need filtration of 10 times the gallons an hour. For instance a 10 gal tank needs 100 gals of filteration an hour.
Also an airstone to provide plenty of oxygen to the water.
I think that is enough for now, hopefully you can post back soon and we can help you further.