I am getting ready to go multi site although the site

I am getting ready to go multi site although the site http://www.fluffey.com had 3000 members in two months that were fake.
After I put captcha on the registration page it is only a one time registration captcha I noticed that no other members or site activity occurred at all.
This is most strange I am looking for a plugin to force users to upload a photo after registration is there one available. Also I am looking to start a dating site is ther any plugins in here for this .

Regards Vincent