1. Fish are cold-blooded, which means their internal body temperature changes as the surrounding temperature changes.
2. About 96% of fish are bony fish. The rest are cartilaginous fish, like sharks, skates, and rays.
3. Electric eels can discharge up to 550 volts, using their shock as an offense for catching food or a defense to escape.
4. Only the front 1/5 of an electric eel contains vital organs. These are located directly behind its head. The rest of the body is comprised of organs that produce electricity.
5. Arowana have the ability to jump out of the water to catch prey such as insects, birds, and bats.
6. More species of fish are found in the Amazon River than in all of Europe.
7. Gar are known as “living fossils,” as their remains have been found dating back to the Cretaceous period.
8. The female seahorse transfers the eggs to the male’s pouch, where they are incubated until birth.
9. Red lionfish are beautiful in the aquarium, but potentially devastating to the Atlantic Ocean, as the first successfully invasive species.
10. The northern snakehead has the ability to gulp air and absorb oxygen through a modified swim bladder that functions much like a lung. This ability allows the snakehead to travel across land to move into new bodies of water.
11. Piranhas hunt in large groups called shoals, or packs.
12. The largest fish in the world is the whale shark, which can grow up to 41 feet long.
13. Baby sharks are called pups.
14. The sand tiger shark is the only shark known to adjust its buoyancy by burping—gulping and expelling air at the surface. This strategy allows the shark to hover nearly motionless in the water column.
15. The archerfish is named for its peculiar adaptation of shooting a stream of water like an arrow at its unsuspecting prey—a tasty insect perched on a branch above the water.
16. The male banggai cardinalfish incubates the eggs in his mouth and continues to hold the young within his mouth cavity after hatching to further protect them.
17. Feather blennies lay their eggs in empty oyster shells. These territorial predators use their strong jaws to snap up and eat small fish and crustaceans that venture too close to the oyster shells.
18. The green moray eel is really brown! The yellow tint of the mucus that covers its body, in combination with the drab background color, gives the fish its characteristic uniform green color.
19. Southern stingrays have a “live birth,” meaning that the eggs hatch within the mother’s body. The pups, up to 10 in a litter, average 9 inches across at birth. Before their live birth, stingrays’ “wings” are curled up like crepes.
20. Burrfish are covered with short, heavy spines that are always erect, unlike their cousins the porcupinefish, which have movable spines.
21. When feeling threatened, pufferfish quickly ingest water to inflate their bodies into a ball several times their normal size.
22. Flounders and sole are fish with both eyes on the same side of their head. One eye actually migrates to the other side during larval development. Like most flatfishes, these bottom-dwellers can change the color patterns on their skin to blend in with their environment. They bury themselves in the sand and, with both eyes facing up, wait to ambush unsuspecting prey.
23. Jellies have been around for more than 500 million years—they pre-date dinosaurs!
24. The lined seahorse is the only seahorse found in the Chesapeake Bay. It camouflages itself by developing leafy appendages and changing colors.
25. In a group of clownfish, there is a strict dominance hierarchy. The largest and most aggressive female is found at the top.
26. Clownfish and sea anemones have a symbiotic relationship. The sea anemone protects the clownfish from predators, as well as providing food through the scraps left from the anemone’s meals. In return, the clownfish defends the anemone from its predators and cleans it from parasites.
27. Some catfish create saucer-shaped nests by fanning the river or lake bottom with their tails. Several thousand eggs are deposited in the nest and are guarded until they hatch.
28. The toothless catfish is not really toothless. It has teeth in the back of its mouth. This bottom-feeder vacuums through the sand to find its food.
29. The Australia grunter fish is so named because it emits an audible grunting sound when handled out of the water.
30. Barramundi, a giant perch found in Australia, changes sex as it grows up, starting as a male. Upon reaching 19.7 inches in length, it become female. These fish can grow to up to 6.5 feet long!