The word lanternfish 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: 19
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (72 words)
anthers, antlers, antsier, arshine, elastin, enfants, ensnarl, entails, enthral, entrain, fainter, fairest, falters, fathers, filters, finales, fireant, fishnet, flasher, hafters, hairnet, halites, halters, hastier, hernial, hernias, infants, inflate, inhaler, inhales, insaner, interns, lantern, lathers, latrine, lifters, linnets, nailers, nailset, nastier, ratfish, ratline, realist, reflash, reliant, renails, rentals, reshift, reslant, restain, retails, retains, retinal, retinas, salient, saltern, saltier, shalier, shifter, slather, slatier, slither, snifter, stainer, sternal, stifler, tanners, tarnish, thinner, tinners, trenail, trifles