help me im new!!!

if you're mixing Ro and dechlorinated tap water, you should be okay. if you're using straight RO, you'll need to pick up some stuff that you can mix with it to replace the natural minerals and other elements that the fish need to have in the water. otherwise the fish will die.
 
I just caught a mistake in my reccomendations, I mis-read your tank dimensions. You still have options, but not as many or as large. With an Oscar I would say one other medium to large cichlid (not larger than the Oscar) plus a pleco or a couple of medium size cats. Or you could go with one oscer and 3 or so smaller fish (large enough not to be eaten) and still put a reasonable clean-up crew in place. But I had 6' x 2' x 2' in mind on my earlier reccomendations, the difference between a 6' tank and a 4' is pretty significant for an oscar (volume wise and territory wise)
Dave
 
thanks for the help eveyone it has been really useful and ill will go do all the things i have to do and then i will start a new thread to decide which fish to put in
 
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