Fun Fat Sleeper Facts For Kids

Christian Mba
Apr 28, 2023 By Christian Mba
Originally Published on Aug 05, 2021
Edited by Luca Demetriou
Fact-checked by Ambuj Tripathi
Fat Sleeper facts on the species found in freshwater channels, muddy ponds, and marshes.
Age: 3-18
Read time: 5.7 Min

Known for its aesthetic appearance, the Fat Sleeper (Dormitator maculatus) is an extremely popular choice for home as well as commercial aquariums. Not much is known about this freshwater species of fish due to a lack of target research on the species except that this freshwater fish is essentially found in channels of fresh water and muddy water in the continents of South America and North America and that they usually only migrate to sea or ocean waters to reproduce or spawn. While Fat Sleeper (Dormitator maculatus) remains classified as one of Least Concern in terms of conservational efforts required to preserve it, one threat that could become substantially more concerning is the loss of its habitat due to humans taking over the species’ natural habitat of brackish waters and mangrove regions along the Atlantic Coast and the Gulf Coast.

Here are some of the most interesting facts about Fat Sleeper (Dormitator maculatus), a fish species that spends most of its life in brackish water. After, do check our other articles on silver dollar facts and angelfish facts as well.

Fat Sleeper Interesting Facts

What type of animal is a Fat Sleeper?

Fat Sleeper (Dormitator maculatus) is a type of fish that belongs to the phylum of Chordata and the family Eleotridae.

What class of animal does a Fat Sleeper belong to?

The Pacific Fat Sleeper is classified as a fish that belongs to the biological family of Eleotridae which are also often referred to as sleeper goby fish.

How many Fat Sleepers are there in the world?

There is no data regarding the number of Pacific Cat Sleepers in the world as of yet to be able to offer an accurate number for their population. However, these fish are classified as a species of Least Concern in terms of their conservation status, thereby establishing that the species is in no immediate danger of endangerment concerning their population.

Where does a Fat Sleeper live?

The Pacific Fat Sleeper fish usually lives in water, usually rivers, streams, and sometimes, seas and oceans.

What is a Fat Sleeper's habitat?

A Fat Sleeper is typically observed to prefer freshwater streams and channels along with brackish and muddy water regions along with mangrove marshes and similar regions. This coastal species of fish is only typically found in lagoons and river mouth waters at the time of spawning or reproduction during their mating season.

Who does Fat Sleeper live with?

Pacific Fat Sleeper is often observed to live in schools or shoals with other Fat Sleepers.

How long does a Fat Sleeper live?

The Pacific Fat Sleeper species of fish generally have an average expected lifespan of about 10-15 years of age.

How do they reproduce?

The Dormitator maculatus or the Fat Sleeper does not have a specific period or season in the year wherein they reproduce. Actively reproducing pretty much all through the year, this coastal species of fish attains sexual or reproductive maturity at about one year of age. It is possible to distinguish between adults who will be reproducing by observing they're darker than usual color at such times. The Pacific Fat Sleeper lays eggs that are roughly 0.3 mm big and this laying of eggs only takes place in lagoons and at the mouths of rivers where the water is considerably less salty than the seas and oceans. Having laid eggs, the male parent makes it his job to protect the nest. The eggs are incubated for about 11 hours, following which larvae hatch that are originally light in color and change over time to become darker shades of brown as they grow.

What is their conservation status?

Pacific Fat Sleeper is classified as a species of Least Concern by the IUCN.

Fat Sleeper Fun Facts

What does Fat Sleeper look like?

With the ability to reach sizes of up to 1 ft (0.3 m) in the most ideal habitats, most of these fish only make it to about 6 in (15 cm) length. Description of this fish is characterized by its flat-shaped heads and its olive-brown colors or darker shades of brown along with stripes of yellow strewn across their scales. The aspect that distinguishes this Pacific fish from other species of Eleotridae is the fact that its pelvic fins do not have a membranous joint but rather are independent.

Fat Sleeper farming is extremely popular due to demand for Fat Sleeper flesh.

How cute are they?

Pacific Fat Sleeper is a very attractive species of fish with its flattish skulls along with thick bodies and a lovely motley of colors.

How do they communicate?

No specific data or theories are available to throw light on the perception and communication abilities of Fat Sleeper fishes.

How big is a Fat Sleeper?

On average, Pacific Fat Sleepers grow to be about 6 in (15 cm) but can grow to be as big as 1 ft (0.3 m) in length, hence the name enormous Fat Sleeper.  

How fast can a Fat Sleeper swim?

There are no specific details regarding the swimming speed of Pacific Fat Sleeper Goby fish species.

How much does a Fat Sleeper weigh?

There are no specific details about the weight of fishes belonging to the species of Dormitator maculatus. However, they are categorized as small fishes.

What are the male and female names of the species?

No specific names have been assigned to the male and female Fat Sleeper fish. In general, males are referred to as male Fat Sleepers, while females are known as female Fat Sleepers.

What would you call a baby Fat Sleeper?

A baby Fat Sleeper fish is generally referred to as larvae and once they grow a little more, as juveniles.

What do they eat?

The Fat Sleeper generally feeds on plants and sediments for its food requirements but has been observed to feed on invertebrate marine creatures too when food availability is sparse.

Are they eaten by humans?

Usually, Fat Sleepers are preferred as pets in aquariums due to their aesthetic appearance.

Would they make a good pet?

While it is difficult to take care of a Fat Sleeper in an artificial environment, if you can offer it space wherein its ideal conditions are met, they would make for very attractive aquarium additions. One thing that must be taken care of is that the other fish in their aquariums must be bigger than it is since these fish eat most things that are about one-fifth of their size. Moreover, having predatory fish in the aquarium would stress these fish out.

Did you know...

The Fat Sleeper does not shy away from eating organisms that are dead.

The Fat Sleeper’s mouth is a fascinating body part due to the size it can spread to. It is a popular fish to be reared in an aquarium.

This freshwater species have an item named after it in the popular game World of Warcraft known as Fat Sleeper bait.

Where to find Fat Sleeper eggs?

The ideal place to find Fat Sleeper eggs is in lagoons, river mouths, and low-salinity brackish coastal waters.

Why does a Fat Sleeper prefer caves?

The Fat Sleeper, not being a very predatory creature, prefers to hide its way into safety. Therefore, one of the most convenient spots for their line of defense is to occupy caves and under loose sediment and mud at the bottom of the water bodies they inhabit.

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! For more relatable content, check out these channel catfish facts, or electric eel facts.

You can even occupy yourself at home by drawing one on our Fat Sleeper coloring pages.

Fat Sleeper Facts

What Did They Prey On?

Invertebrate marine animals

What Type of Animal were they?


Average Litter Size?


How Much Did They Weigh?

0.3 oz (8.5 g)

What habitat Do they Live In?

muddy ponds, freshwater channels, salty mangrove regions

Where Do They Live?

south america and north america

How Long Were They?

Up to 12 in (30 cm)

How Tall Were They?








Scientific Name

Dormitator maculatus

What Do They Look Like?

Brown body with darker brown, blue and green bands. A Blue spot behind the head over the pectoral fin

Skin Type


What Are Their Main Threats?

loss of habitat

What is their Conservation Status?

Least Concern
We Want Your Photos!
We Want Your Photos!

We Want Your Photos!

Do you have a photo you are happy to share that would improve this article?
Email your photos

More for You


See All

Written by Christian Mba

Bachelor of Science specializing in Computer Science

Christian Mba picture

Christian MbaBachelor of Science specializing in Computer Science

Christian Mba is an experienced blogger and content writer with over a decade of experience. He holds a Bachelor of Science degree in Computer Science from Nigeria and has a keen interest in Python programming. Along with his writing and blogging expertise, he is also an SEO specialist with more than six years of experience. Chris, as he is commonly known, has a passion for music and enjoys playing the piano.

Read full bio >
Read the DisclaimerFact Correction