we have a total of four platys. two males, two females. the 'little' female got ich awhile back. we got the meds and cleared her up just fine. however, since then, the other three constantly pick on her. she goes into hiding and within just a few mintues they flush her out and pick on her again. they chase her around the entire tank while 'guarding' the other female (which btw we think is pregnant). im afraid theyre going to stress her out so much that she dies. any advice?