If you had std and left untreated and caused hydrosalphinx in one tube, does still taking antibiotics is necessary? or if it is blocked than no need

Get treated: It is always best to be treated. With hydrosalpinx, it might be the infection is long gone and antibiotics won't help. However, it isn't certain, and treatment might help clear it up and/or reduce the chance you will be infertile. See a gynecologist, preferably one with expertise in STDs and other infections, and follow her or his advice. Good luck!