I agree with the above.
Loons will need lots of space ,and are quite territorial. Along with lots of water they will also need very clean water. Not the muddy flith ducks are happy to swim in. Either daily water changes or a strong filtration system.
Also no ,without permits they are not legal to own ,as all loon species are native to north america.
Also fish eating birds REAK like fish. If you ever should wish to smell a loon, don't. They smell bad.