Hi Inocel and welcome!
I have a 10 gallon Eclipse that I keep my tropical fish in and they are great tanks! I love the Biowheel especially. Unfortunately, like you, when I first came here I had my fantail and comet both in that tank, and the fantail was very ill. Thanks to the help and advice I got from everyone here, they are now in a 30 gallon and doing fine.
Your comet is very pretty. Florence (my comet) looked like that when she was small, but now that she has grown and aged she is solid silver...just a beautiful fish. Thats her and Moby, my fantail, in my avatar, dancing. They LOVE to dance, lol!
When you get your new tank, be sure to come on here and ask for help as everyone will quickly answer your questions and help you keep your tank on the right track. It takes time and patience.
I am thrilled today because for the first time since I've cycled, and its been over 2 months, I finally have readings of
0 ammonia and 0 nitrites!!!!!!
It doesn't take much to thrill me, as you can tell, lol!
Good luck! Ich is very treatable if you catch it quickly and follow the advice they'll give you here.
And also, fish
always act like they're hungry! Mine are little pigs...flying up to the tank walls every time they see me walk by, hoping for food!

You truly can't go by how they act or you'd be feeding them once an hour!