Check out http://www.fishdb.com">www.fishdb.com</a> You can create a virtual tank to check compatability of all your planned inhabitants or just check compatability between two species. It also gives you suggestions on how to minimize problems.
According to the website, there is low risk of the Lawnmower Blenny terrorizing the Diamond Goby. The suggested solution is use an 80G or larger tank. Hope that helps...