This is the same response I gave for your tetra thread.
What other fishes are in the tank?
How long has the tank been set up for?
Do you have a picture of the tank?
What are the tank dimensions (length x width x height)?
Please note, not all members of this forum use gallons and we don't all know how big a 240 gallon tank is. The tank could be tall and narrow or wide and low. These factors affect what fish can be kept.
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).
Without the above information, you are asking the equivalent of how long should a piece of string be