Goldfish have teeth in the back of their throat.
27. In 2013, a man named Naylor in Blackpool made a lifejacket for a goldfish named Einstein that wasn't able to swim after falling ill.
28. Freshwater fish only "drink" water through their skin via osmosis, while saltwater fish also drink water through their mouths.
29. The Coelacanth is a prehistoric fish which is related to reptiles and mammals more than modern fish. It was thought to have gone extinct 65 million years ago until a fisherman caught one in 1938.
30. Up to 40% of tuna imported to the U.S. from Thailand is illegal or unreported, followed by up to 45% of Pollock imports from China, and 70% of salmon imports.
The notion that goldfishes have a memory span of only few seconds is nonsense. In fact, they can be trained to react to light signals and perform tricks.
32. The blood of eels is more poisonous than some snake venom, but cooking or digesting the blood renders it harmless.
33. Goldfishes were originally silver. They were bred by the imperial family of Song Dynasty in ancient China until they became yellow because they really liked yellow.
34. Seahorses engage in an eight-hour courtship dance which includes spinning around, swimming side by side and changing colors.
35. A Seahorse is the only fish to have a neck.
Since sunfish are susceptible to skin parasites, they sometimes break the surface of the water with its dorsal fin and beak to attract the attention of a gull or similar seabird. The seabird will then dig worms and other stubborn parasites out of the fish's skin.
37. Female fishes have been observed to sometimes fake orgasms to dupe males into thinking they have copulated. They then swim off to find a better partner.
38. There is a deep sea fish that takes advantage of the fact that fishes can't see a red light, and illuminates its prey with a beam of red bioluminescence so that it can hunt with an effectively invisible beam of light.
39. In a narrow island in the Tarn River in France, giant 50-pound European catfishes beach themselves in order to capture and eat pigeons.
40. Scientists have found fishes and some other aquatic animals living under Antarctica, beneath 740 meters of ice in a 10-meter-deep section of water. Scientists are still unsure of how they manage to sustain themselves.
Fish can learn to pull a string to dispense food, and some have also figured out how to use a tool to pull the string as they swim by.
42. The Blue Tang Fish 'Dory from Finding Nemo' is poisonous to eat, has venomous barbs on their back, and will cut you.
43. A popular 17th-century Chinese concoction of pickled fish and spices called "kê-chiap" was picked up by the English explorers. The English settlers took it with them to the American colonies. This concoction became quite popular and we know it today as Ketchup.
44. There is a fish called the "Bony-eared ass fish". It has the smallest brain to body ratio of all known vertebrates.
45. Round goldfish bowls are banned in Monza (Italy) because 'a fish kept in a bowl has a distorted view of reality'.
Electric Eels are apex predators because none of the animals that can eat them want to get shocked.
47. Tennessee Aquarium has a twitter account that sends out tweets powered by an electric eel.
48. Eulachon fish is so oily that it can be set on fire and it was used as a source of light by Nisga'a people.
49. There is a species of fish named Pacific leaping blenny that lives on land all its adult life.
50. There exists a type of fish named Gardneri Killifsh that can live out its entire life cycle in the footprint of an elephant.