Producers Joe Ruby and Ken Spears both worked for Hanna-Barbera, but left to form their own animation production company, Ruby-Spears Enterprises. Fangface was the first cartoon series produced under their new banner.
There were a number of "rules" regarding Fangface. First, any image of the moon would transform Fangs into Fangface and any image of the sun would change Fangface back to Fangs. When Fangface would emerge, his first instinct was normally to beat up Pugsey. He normally had to be reminded that Pugsey was his pal. If Fangface sees or hears the mention of food or any food item, he tries to eat Pugsey. If he actually succeeds in stuffing Pugsey in his mouth, Biff or Kim would have to rub his foot in order to get him to relax and cough up Pugsey. Finally, if Fangface sees his reflection in a mirror, he goes crazy with howling and barking.