What are the tank dimensions (length x width x height)?
What is the GH (general hardness), KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).
Guppies do best in water with a pH above 7.0 and a Gh around 200ppm or above.
Neons, Corydoras and rams come from water with a pH below 7.0 and a GH below 100ppm.
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Bolivian rams are quite peaceful and you can keep one on its own. In fact, unless you buy a bonded pair or a group and let them pair off naturally, you are better off with only one fish. If you get 2 males or 2 fish that don't like each other, they fight. So just get one.