Here are the top six largest fish species (within around 33,100 described species).
But, first of all, what is a fish? At first, it looks like an easy question, but in fact, it is not. There are a wide range of animals we call “fish”, so it is not easy to define what makes a fish “a fish”. A general description: “a fish is any member of a paraphyletic group of organisms that consist of all gill-bearing aquatic craniate animals that lack limbs with digits” (Wikipedia).
All fishes have a brain protected by a braincase, and an obvious head region with eyes, teeth, and other sensory organs.
- are vertebrates with vertebrae protecting the spinal cord.
- live in water.
- breathe primarily with gills rather than lungs.
- have paired limbs, in the form of fins that aid in locomotion.
- are unable to regulate their own internal body temperatures.
- are covered with scales that protect their bodies.
But there are exceptions: hagfish aren’t vertebrates and don’t have scales; mudskippers can live outside the water, lungfish use lungs to breathe, lampreys don’t have paired fins, and tuna are warm-blooded.
Fish can be found in nearly all aquatic environments, from high mountain streams (e.g., char and gudgeon) to the abyssal and even hadal depths of the deepest oceans (e.g., gulpers and anglerfish); in environments as hot as 104°F/40°C and as cold as 28°F/-2°C.
And here are our top six largest living fish, in reversed order.
6. Great White Shark (up to 6.4 meters / 21 feet)
The great white shark (scientific name: Carcharodon carcharias) is the largest predatory fish on Earth. According to the Guinness World Records Book, full-grown adults are average 4.3–4.6 m (14–15 ft) in length, and generally weigh 520–770 kg (1,150-1,700 lb). But they can grow up to 6.4 meters / 21 feet, and there are many claims of huge specimens up to 10 m (33 ft) in length (most of these claims are unverifiable, and probably false).
5.Beluga (sturgeon) (up to 7.2 meters / 23 feet 8 in)
The beluga or European sturgeon (Huso huso) is a large predator which feeds mostly on fish, also rarely consuming waterfowl and seal pups. It is a species of anadromous fish (the fish migrate from the sea up into freshwater to spawn; examples are salmon and striped bass – Greek: ἀνά ana, “up” and δρόμος dromos, “course”) in the sturgeon family (Acipenseridae) of order Acipenseriformes. It is found primarily in the Caspian and Black Sea basins, and occasionally in the Adriatic Sea.
The largest accepted record is of a female taken in 1827 in the Volga estuary at 1,571 kg (3,463 lb) and 7.2 m (23 feet 8 in). Several other records of aged sturgeon exceed 5 m (16 ft). These great sizes mark the beluga as the largest freshwater fish in the world.
4. Greenland Shark (up to 7.3 meters / 24 feet)
Greenland Shark lives farther north than any other shark species. It is one of the largest living species of shark, of dimensions comparable to those of the great white shark. Greenland sharks grow to 6.4 m (21 ft) and 1,000 kg (2,200 lb), and possibly up to 7.3 m (24 ft) and more than 1,400 kg (3,100 lb). However, most Greenland sharks observed have been around 2.44–4.8 m (8.0–15.7 ft) long and weigh up to 400 kg (880 lb).
The Greenland shark has a sluggish look, with a thickset, cylindrical body and a small head with a short snout and tiny eyes. Their maximum speed is a lethargic 1.7 miles per hour, many are almost blind, and they are happy to eat rotting carcasses: they particularly prefer the tastes of Narwhal and Beluga whale carcasses, and they sometimes participate in cannibalism. Furthermore, these sharks also enjoy seals, cetaceans, sea lions, salmon, lumpfish, halibut, char, capelin, herring, and other fish.
3. Basking Shark (up to 8 meters / 26 feet)
The basking shark (Cetorhinus maximus) is the second-largest living fish on Earth and one of three plankton-eating sharks besides the whale shark and megamouth shark. It can be found in all the world’s temperate oceans. It is a slow-moving filter feeder and has anatomical adaptations for filter feeding, such as a greatly enlarged mouth and highly developed gill rakers. Adults typically reach 6-8 meters (20-26 feet) in length.
2. Giant Oarfish (up to 11 meters / 36 feet)
Giant Oarfish is the longest bony fish on Earth. Although they commonly measured up to 3 meters (9.8 feet) in total length, they can grow a record length of 11 meters (36 feet). They are rarely seen because the Giant Oarfish lives at depths around 3,300 feet (1,000 meters).
1. Whale Shark (12.65 meters /41.50 feet) – the largest fish in the world
The whale shark (Rhincodon typus) is the largest known extant fish species. It is a slow-moving filter feeding shark. The largest confirmed individual had a length of 12.65 m (41.50 ft) and a weight of about 21.5 metric tons (47,000 lb), and unconfirmed reports of considerably larger whale sharks exist. Claims of individuals over 14 m (46 ft) long and weighing at least 30 metric tons (66,000 lb) are not uncommon.
Whale sharks have a mouth that can be 1.5 m (4.9 ft) wide, containing 300 to 350 rows of tiny teeth and 10 filter pads which it uses to filter feed.
The video below captured and submitted by GoPro Awards recipients shark biologist and freediver Ocean Ramsey and Juan Oliphant. They swim with whale sharks in the Philippines to document migrating populations. Whale shark populations are at an all-time low due to finning, fishing bycatch, entanglement, speedboat prop collisions, and death by ingestion of floating debris.
Some other big fishes
There are some other living big fish species which can be included in this list. For example, the common thresher (Alopias vulpinus), can grow to 7.6 m (25 ft) and weigh over 510 kg (1,120 lb), but much of its length is comprised by its extreme tail, so I didn’t include it in the list.
Another example, the Sawfish (Pristiformes): these little-known cartilaginous fishes are often reported to attain huge sizes. The definitive largest species is not known, although the smalltooth sawfish (Pristis pectinata) and the green sawfish (P. zijsron), at up to reportedly 7.6 and 7.3 meters (25 and 24 feet), respectively, may be the largest. Weights of up to 1,955 kg (4,310 lb) have been reported, possibly for the smalltooth species, but are not verified. The large-tooth sawfish (P. perotteti) and freshwater sawfish (P. microdon) can both exceed 6.5 meters (21 feet). Much of their length is comprised by their long “saw” noses.
The heaviest living bony fish: Ocean sunfish
The ocean sunfish, or common mola, Mola mola is the heaviest of the bony fish in the world. The mature ocean sunfish has an average length of 1.8 meters (5.9 feet) and a fin-to-fin length of 2.5 meters (8.2 feet). The average weight of mature specimens can range from 247 to 1,000 kg (545 to 2,205 lb) Even larger individuals are not unheard of. The maximum size is up to 3.3 meters (10.8 feet) in length 4.2 meters (14 feet) across the fins and up to 2,300 kg (5,100 lb) in mass.
Update (July 24, 2017): Researchers Just Discovered A New Species Of the Ocean Sunfish
On July 20, 2017, National Geographic has announced that researchers have discovered a new species of the Ocean Sunfish. It has been named the Hoodwinker sunfish (Mola tecta) and is the first species of Ocean Sunfish to be identified in 130 years – somehow it has escaped taxonomy records for almost three centuries.
Here is the video published by the National Geographic below:
Megalodon – The largest shark ever lived on earth (up to 18 meters / 59 feet)
Megalodon (meaning “big tooth”, from Ancient Greek) is an extinct species of shark that lived approximately 15.9 to 2.6 million years ago, during the Cenozoic Era (middle Miocene to end of Pliocene). Fossil remains suggest that this giant shark reached a length of 18 meters (59 feet).
Megalodon had the most powerful bite of any creature that has ever lived: it is estimated that the bite force the Megalodon’s jaws could generate was somewhere in the vicinity of 108,514 N – 182,201 N (11-18 tons of force). For reference, this is about 6-10 times the biting power of a Great White Shark and 18-30 times that of a Lion. It is strong enough to crush an automobile and even far exceeded that of the Tyrannosaurus rex, which was capable of a maximum bite force of 35,000 to 57,000 newtons at its back teeth.
Largest known fish ever lived: Leedsichthys (22 meters / 72 feet)
The largest-ever known bony fish was Leedsichthys, of the Jurassic period in what is now England. Estimates of the size of this fish range from 21 to 27 meters (69 to 89 feet) and mass from 20 to 50 tons. Maximum size of 22 meters (72 feet) and 25–30 tons has been deemed to be most realistic.
- What is a fish? on Evolution.Berkeley.Edu
- Fish on Wikipedia
- Greenland shark on Wikipedia
- Beluga (sturgeon) on Wikipedia
- Basking shark on Wikipedia
- Whale shark on Wikipedia
- Smalltooth sawfish on Wikipedia
- List of largest fish on Wikipedia
- Megalodon on Wikipedia
- Leedsichthys on Wikipedia
- Ocean sunfish on Wikipedia