The word harvestfishes 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: 24
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (68 words)
aeriest, ashiest, asserts, atheise, easiest, faeries, fairest, fathers, feather, festers, festive, fiestas, fishers, freesia, hafters, harvest, hastier, hearses, hearths, heaters, heather, heavers, heavier, hefters, heftier, heifers, heiress, hessite, hissers, rashest, ratfish, reheats, resaves, reseats, reshave, reshift, resifts, resists, restive, revises, sassier, satires, seaters, seriate, shavers, sheathe, sheaths, sheaves, sherifs, shifter, shivers, shrifts, siestas, sievert, sifters, sisters, starves, stashes, stivers, strifes, strives, teasers, thieves, thrives, trashes, tresses, verists, veritas