How can I reduce spam blog comments???

Hello,

We have a blog and we get spam bots filling out comments on our posts in droves… and it seems to be getting worse. We will get 1000-2000+ within a matter of weeks.

I see the options in wordpress under Settings > Discussion but I feel like we need a captcha field or something of the like… Maybe there is another better option? Any help would be greatly appreciated.

Thanks, Ben