You maybe have been looking for Fireworm (Species)

Fireworm, the only female Monstrous Nightmare in the book, is the bright red, stubborn, and tenacious dragon of Snotface Snotlout. She also loves to sneer about stuff she hates, like Toothless.

How to Train Your Dragon

Snotlout captured a Monstrous Nightmare and named her Fireworm. She is reasonably brave in the book; for instance, she leads the Green Death to the Purple Death so that they would kill each other.

How to Be a Pirate

Fireworm sniffs out Grimbeard the Ghastly's false treasure he buried on the isle of Skullions.

How to Speak Dragonese

How to Twist a Dragon's Tale

How to Break a Dragon's Heart

How to Steal a Dragon's Sword

How to Train Your Dragon (film)

Fireworm makes no appearance in the film; however, a Monstrous Nightmare named Hookfang is trained by Snotlout. Hookfang is the name of Stoick's in the books. Unlike his Fireworm, Hookfang is male and has a very different personality. Unlike Hookfang, Fireworm is very obedient towards Snotlout. Hookfang in the movie seems to show grudging respect towards Hiccup, whereas Fireworm in the book shows as much animosity as her owner towards him.