The word guitarfishes is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 20
Highest Scoring Words With Friends™ Plays In The Letters
Seven Letter Word Alert: (59 words)
afright, aigrets, airiest, ashiest, augites, fairest, fairies, fathers, fatigue, fiestas, fighter, figures, fishers, fishier, fissure, fraught, freight, frigate, frights, fussier, gaiters, garfish, gashers, gassier, gathers, geishas, guitars, gushers, gushier, gustier, gutsier, hafters, hastier, hirsute, hissier, irisate, ragfish, rashest, ratfish, reshift, resifts, resight, sagiest, satires, sherifs, shifter, shrifts, sifters, sighers, sighter, stagers, stagier, strifes, suiters, surfeit, tigress, tigrish, trashes, triages