| Having four parts: Prefix | 25 |
| Four: Prefix | 13 |
| Four, for starters? | 19 |
| Four (pref.) | 12 |
| Aquarium beauty | 15 |
| Brightly colored tropical fish | 30 |
| One more than tri- | 18 |
| Prefix with fluoride | 20 |
| "Four" at the fore | 28 |
| Prefix with chloride | 20 |
| Neon aquarium fish | 18 |
| Aquarium brightener | 19 |
| Tank swimmer | 12 |
| Neon ___ | 8 |
| Four, before | 12 |
| Fish in a tank | 14 |
| Small aquarium fish | 19 |
| Prefix with meter or gram | 25 |
| Pet-shop swimmer | 16 |
| Neon swimmer | 12 |
| Neon fish | 9 |
| Neon ___ (fish) | 15 |
| It comes before penta- | 22 |
| It can add color to the tank | 28 |
| Half of octa- | 13 |
| Four fore? | 10 |
| Fish tank favorite | 18 |
| Exotic fish | 11 |
| Colorful tank fish | 18 |
| Aquarium inhabitant | 19 |
| Aquarium acquisition | 20 |
| Vampire ___ (fanged fish) | 25 |
| Tropical, freshwater fish | 25 |
| Tropical American finch | 23 |
| Tri, plus one | 13 |
| Tri- plus one | 13 |
| Tri plus one | 12 |
| Tankmate for an angelfish | 25 |
| Tank brightener | 15 |
| Prefix with meter or methylene | 30 |
| Prefix with hydrozoline | 23 |
| Prefix with -zene | 17 |
| Prefix with -cycline | 20 |
| Prefix meaning "4" | 28 |
| Prefix for meter or spore | 25 |
| Popular household fish | 22 |
| Popular aquarium beauty | 23 |
| Pet shop fish | 13 |
| Pet fish | 8 |
| Penta- minus one | 16 |
| One more than tri | 17 |
| One more than "tri" | 29 |
| Octa- halved | 12 |
| Octa- divided by two | 20 |
| Neon -- | 7 |
| Neon _____ | 10 |
| It may help fill your tank | 26 |
| Hedron lead-in | 14 |
| Half of octo- | 13 |
| Half of octa | 12 |
| Guppy neighbor, maybe | 21 |
| Fore for four? | 14 |
| Flashy tank swimmer | 19 |
| Flashy tank fish | 16 |
| Flashy little fish | 18 |
| Fish-tank favorite | 18 |
| Fish that sounds like it should be in a group of four | 53 |
| Fish store favorite | 19 |
| Fish or prefix | 14 |
| Eye-catching swimmer | 20 |
| Eye-catching aquarium denizen | 29 |
| Discus ___ (aquarium fish) | 26 |
| Di- doubled | 11 |
| Denizen of an aquarium | 22 |
| Cousin of quadri- | 17 |
| Chloride lead-in | 16 |
| Brightly-colored tropical fish | 30 |
| Brightly-colored fish | 21 |
| Bi plus two | 11 |
| American fish | 13 |
| African long-finned ___ (fish) | 30 |
| "Four" before words, sometimes | 40 |
| ''Four'' at the fore | 36 |
| Foursome | 8 |
| Group of four | 13 |
| Four of a kind | 14 |
| Any foursome | 12 |
| The classical elements, e.g. | 28 |
| Monopoly's railroads, e.g. | 30 |
| Four-note chord | 15 |
| Trio plus one | 13 |
| The women in "Little Women," e.g. | 43 |
| Gift of calling birds, say | 26 |
| Fourfold | 8 |
| Cat's paws, e.g. | 20 |
| Groups of four | 14 |
| Quaternities | 12 |
| Double duos | 11 |
| The Beatles and others | 22 |
| A word of four letters | 22 |