| Wrymouth's cousin | 21 |
| Wriggly one | 11 |
| Wriggling swimmer | 17 |
| Wiggly swimmer | 14 |
| What a sniggler snares | 22 |
| Vinegar ___ (minute worm) | 25 |
| Vinegar ___ (certain worm) | 26 |
| Undulate swimmer | 16 |
| Underwater slitherer | 20 |
| Underwater power source? | 24 |
| Underwater current generator | 28 |
| Unagi, in sushi bars | 20 |
| Unagi, in sushi | 15 |
| Unagi, in Japanese restaurants | 30 |
| Unagi, in a sushi restaurant | 28 |
| Unagi, e.g. | 11 |
| Unagi, at a Japanese restaurant | 31 |
| Unagi roll ingredient | 21 |
| Unagi or anago, e.g. | 20 |
| Unagi at a sushi bar | 20 |
| Unadon ingredient | 17 |
| Unadon fillets | 14 |
| Traditional London pie-and-mash ingredient | 42 |
| This may be spitchcocked | 24 |
| Third-longest river of California | 33 |
| Thing in the sea | 16 |
| That's amoray | 17 |
| That's a moray? | 19 |
| Teriyaki option | 15 |
| Teleost | 7 |
| Swimming spaghetti monster? | 27 |
| Sushi's unagi | 17 |
| Sushi-bar offering | 18 |
| Sushi-bar delicacy | 18 |
| Sushi stock | 11 |
| Sushi roll option | 17 |
| Sushi possibility | 17 |
| Sushi ingredient, perhaps | 25 |
| Sushi dish | 10 |
| Sushi center, perhaps | 21 |
| Sushi bar selection, perhaps | 28 |
| Sushi bar order, perhaps | 24 |
| Sushi bar fish | 14 |
| Subject in a slippery simile | 28 |
| Stunner underwater | 18 |
| Stork's mouthful | 20 |
| Squiggly swimmer | 16 |
| Spitchcocked food | 17 |
| Spiny ___ | 9 |
| Spicy tuna alternative | 22 |
| Spearfisherman's catch | 26 |
| Spawner in the Sargasso Sea | 27 |
| Soul of the dead, in Philippine folklore | 40 |
| Sometimes shocking swimmer? | 27 |
| Something to sniggle for | 24 |
| Snipefish, e.g. | 15 |
| Sniggler's wriggler | 23 |
| Sniggler's wiggler | 22 |
| Sniggler's victim | 21 |
| Sniggler's target | 21 |
| Snake-like swimmer | 18 |
| Snake impersonator | 18 |
| Smoked or jellied dish | 22 |
| Slithery underwater predator | 28 |
| Slithery sea creature | 21 |
| Slithering swimmer | 18 |
| Slippery guy | 12 |
| Slippery fish? | 14 |
| Slippery fellow | 15 |
| Slippery catch | 14 |
| Slimy swimmer | 13 |
| Slimmer swimmer | 15 |
| Slime ___ (hagfishÂ’s nickname) | 34 |
| Slim, slimy swimmer | 19 |
| Sinuous sea dweller | 19 |
| Silver ___ (mature elver) | 25 |
| Short-finned ___ | 16 |
| Shocking swimmer? | 17 |
| Shocking sea critter? | 21 |
| Shocking fish, at times | 23 |
| Shocker, perhaps | 16 |
| Sea snake | 9 |
| Sea shocker | 11 |
| Sea creature that may be smoked | 31 |
| Scary swimmer in "The Deep" | 37 |
| Scaleless swimmer | 17 |
| Sashimi option | 14 |
| Sashimi fare | 12 |
| Sargasso squirmer | 17 |
| Sargasso snake | 14 |
| Sargasso Sea fish | 17 |
| Sargasso Sea dweller | 20 |
| Sapporo seafood | 15 |
| Sand or sea critter | 19 |
| River zapper | 12 |
| River lurker | 12 |
| Relative of a wrymouth | 22 |
| Reedfish lookalike | 18 |
| Protein source for Maoris | 25 |
| Potentially shocking fish | 25 |