| Family | Scientific Name | Author | Year | Common Name |
| Belonidae | Tylosurus acus | (Lacepède) | 1803 | Atlantic Agujón |
Tylosurus acus
Unique Characters: Beak relatively short, about twice the length of rest of head. A weak, darkly pigmented lateral keel on each side of caudal peduncle. Lower lobe of caudal fin much longer than upper lobe. Juveniles with an expanded black lobe in the posterior part of the dorsal fin. Dark blue stripe on side. Body rounded or squarish in cross-section. No vertical bars present. Anal-fin rays 13-24. Caudal peduncle not strongly depressed. Caudal peduncle deeper than wide. Gill rakers absent. Dorsal-fin rays 21-26. Dorsal- and anal-fin lobes relatively low compared to body length (10.1 -13.3 and 9.7-11.7 times in body length, respectively). Pectoral and pelvic fins relatively short (8.0-12.4 and 10.0-14.1 times in body length, respectively). Upper and lower jaw teeth straight at all sizes. Left gonad absent or greatly reduced in length.
Similar Species: Houndfish Tylosurus crocodilus. Beak relatively short, about 1-1/2 times the length of rest of head. A small black lateral keel on each side of caudal peduncle. Lower lobe of caudal fin much longer than upper lobe. Juveniles with an expanded black lobe in the posterior part of the dorsal fin. Blue stripe on side. Body rounded or squarish in cross-section. No vertical bars present. Anal-fin rays 13-24. Caudal peduncle not strongly depressed. Caudal peduncle deeper than wide. Gill rakers absent. Dorsal-fin rays 21-26. Dorsal- and anal-fin lobes relatively high compared to body length (5.4-10.6 and 5.5-8.0 times in body length, respectively). Pectoral and pelvic fins relatively long (6.6-8.3 and 7.3-10.6 times in body length, respectively). Upper and lower jaw teeth point distinctly anterior in juveniles. Left gonad distinct although shorter than right.
Gallery
