The Smallest Fish in the World

Like the smallest shark in the world, it’s highly likely that we have yet to discover the smallest fish in the world, due to the very nature of small fish.

Our list of fish is limited to those under an inch. The smallest being 0.24 inches (6.2 mm) and the largest being .98 inches (2.5 cm). To give you a frame of reference, common neon tetra aquarium fish are 1.5 inches (3.8 cm) long.

Some of the fish on our list live so far down in the ocean depths that humans have only seen them a handful of times. But, two are actually quite popular among those who keep fish tanks as pets.

Keep reading for a list of the eight smallest fish in the world, as well as more information about these interesting creatures. Since each gallon of water should only house one inch of fish, many hobbyists find they can fit more of these tiny pets into their tanks.

smallest fish in the world photocorynus spiniceps
Smallest Fish in the World: Photocorynus Spiniceps

Quick Facts

  • The Photocorynus spiniceps, a type of angler fish, is the smallest known fish in the world. The males are parasitic and attach themselves to the female; they only grow to be 6.2 millimeters long.
  • The Paedocypris progenetica, a small female relative of the carp, is typically approximately 7.9-millimeters long. They are most commonly found in the peat of one central swamp located in Indonesia. This area’s acidic levels are 100 times greater than those caused by acid rain!
  • The Chili Rasbora is a native of Borneo and very popular among aquarium and nano aquarium fish lovers because of its bright, intense colors. This small fish is also known to be active and thrive in schools.

The 8 Smallest fish in the world

Keep reading below to learn about the 8 smallest fish in the world.

Photocorynus spiniceps

The Photocorynus spiniceps, or anglerfish, is the smallest fish that has been discovered. It certainly can also be classified as an ugly fish of the world. The males only grow to be 6.2 mm long, which is shorter than a quarter of an inch! These male Photocorynus spiniceps attach to females for their entire lives after they find one due to their small size. Meaning the female must provide food and shelter for both herself and her parasitic partner.

The females of this species can grow up to 50 millimeters in length, which is twice as long as the eighth smallest fish on this list.

Did you know that anglerfish live in the deep sea and use a bio luminous bulb to trick their prey into swimming straight into their mouths? The female Photocorynus spiniceps, like other anglerfish, has teeth very similar to a Fangtooth, so her prey is unlikely to escape!

The males of this species, who look like thin strips of paper, spend their lives glued to the female. They get their nutrients from whatever she eats, so she’s always eating for two.

Every day, new species are discovered. It’s not unheard of for tiny fish to go unnoticed. In a few years, the Stout infantfish and the male anglerfish might not even make it to third place on this list!

Stout infantfish

The Stout infantfish, scientific name Schindleria brevipinguis, is the smallest fish of record because both the male and female are of a similar small size.

While some experts say males are no bigger than 6.5 millimeters, others maintain that the maximum size is closer to 7.5 millimeters. On the other hand, females measure between eight and nine millimeters.

The Stout infantfish is second on our list because, believe it or not, the smallest female size is 6.5 millimeters and the largest male size is only 6.2 millimeters. If you’re imagining a petite yellow fish that looks like a baby banana, then you’re thinking of this species most commonly found in Australia’s Great Barrier Reef!

Paedocypris Progenetica

The Paedocypris progenetica, a tiny relative of the carp, is an amazing fish! The smallest recorded specimen was only 7.9 mm long. They are found living in stagnant water conditions that 100 times more acidic than acid rain. They were first discovered in 1996 but weren’t correctly classified as their own species until 2006.

Paedocypris progenetica
Paedocypris progenetica

Dwarf pygmy goby

The male Dwarf pygmy goby, Pandaka pygmaea, also known as the Phillipine goby, is only nine millimeters long. That’s about one-third of an inch. The most this fish can grow is 1.1 centimeters in length.

On the contrary, its female counterpart can grow to 1.5 centimeters. The species is usually found in areas such as the province of Palawan in the Philippines, Culion Island, Singapore, Bali and other mangrove swamps or brackish water locations.

The Dwarf pygmy goby, a fish found in Southeast Asia, is facing extinction. These creatures have blunt heads and are mostly see-through, with dark spots near their fins being the only significant source of color.

dwarf pygmy goby
Dwarf Pygmy Goby

Midget dwarf goby

The Trimmatom nanus, or Midget dwarf goby, is the fifth smallest fish. They grow to a size of 10mm and are brightly red-orange with large eyes and fins that look like feathers.

These fish come from the Indian Ocean near Maldives and the western Pacific Ocean. They live 66-98 feet below sea level and can be seen in coral reefs that are 16-116 feet deep.

Until recently, not much was known about dwarf gobies. These pretty little fish were discovered in 1981 and held the title of smallest fish in the world until 2004.

Chili Rasbora

Chili Rasboras, or Boraras brigittae, are only a little over three-quarters of an inch long, at 19 millimeters. They get their name from their bright red coloration. Chili rasboras make good additions to aquariums because they’re small and don’t need much room to swim.

The native Borneo fish, Mosquito Rasboras, are a lovely dazzling red with shiny black stripes on their fins and also one running along either side.

Celestial Pearl Danio

The first fish species on our list is the Celestial Pearl Danio, more formally known as Danio margaritatus. This tiny fish only grows to be around 25 millimeters or just barely under an inch in length, making it a popular choice for nano aquariums.

The little beauties have a deep blue color on their bodies, with goldish white spots all over. Females have bright orange on their fins that fades to clear. Whereas males have red and black on their fins, and both sexes have black lines on their Celestial Pearl Danios are sometimes referred to as galaxy rasboras.

Celestial Pearl Danio
Celestial Pearl Danio

Corfu dwarf goby

The Knipowitschia goerneri, which is more commonly referred to as the Corfu dwarf goby, is only an inch long at most. These fish have either a white or tan body with brown spots sprinkled over the top half.

The Corfu dwarf goby is a strangely shaped fish. Appearing almost asymmetrical and squeezed out of a tube rather than swimming gracefully like other fish. This species has only ever been found in one lagoon in Greece. However, when scientists went to study the population in 1991, they could not find a single fish. The Corfu dwarf goby was believed extinct for many years after this initial survey.

However, nearly twenty years after their supposed extinction, nine new Corfu dwarf goby were discovered living in the same lagoon.

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