that is a very odd shaped tank. hmmm.
First of all it sounds like you haven't cycled your tank, this is probably why you are loosing fish. The cycle is the process when the tank builds up bacteria that break down waste in the tank. Waste(food, fish waste, ect) creates ammonia that will kill fish. The bacteria will break down the ammonia to nitrite and then from nitrite to nitrate. This is a slow process and takes several weeks.
Instead of taking the water to be tested I suggest you all pick up your own liquid kit. You will need to do a lot of tests and water changes over the next while to keep the fish in the tank alive. Don't start adding chemicals to the tank, these things are short term fixes and usually cause more problems than they solve. All you need is a good water conditioner... something like Seacheams PRIME would be very helpful.
I would next suggest you check out some articles on this site. There is a thread stickies at the top of the forum with good articles. They will break down the whole cycle process for you so you know what we are talking about. lol.
As for fish.. I'm really not sure what to stock in a tank that size.. It's 60 inches tall and about a foot wide?? with the dimensions you gave I got 36 gallons which would be a fantastic size tank.. if not for a crazy shape. hmm.. usually I suggest guppies for tall tanks, they are good all over swimmers.
You probably need to up your filtration and should add an airstone. With so little surface area your fish probably need the added help for oxygen.