To help reduce Spam comments on your WordPress website, you can and should use Akismet. It seems to be the most accurate and effective plugin. That's the only plugin to control spam that I run in all the sites I manage. There's one more thing you can do to improve your site's SPAM catching ability: Blacklisted Words.
Here's the best list of blacklisted words for your WordPress website. You can just go to your comment moderation options and add them there. Get the file right here. WordPress Blacklist Words.
What does it do?
Protects WordPress from Spam
Saves you time, (moderate real comments, not spam)
Reduces load times (less spam comments to display and clean up make your site run better)
This list is for English words to blacklist and protect you from spam. If you have an interest for other languages, please let me know in the comments. I'll be happy to compile one for your language.