Did you know the Upside Down Catfish, also known as Synodontis nigriventris, can be found in Egyptian art and tomb walls dating back four millennia ago?

Unfortunately for our dear ancestors, they can only wonder and admire this bizarre-looking fish as they don’t have access to the information you now have. So dive in and learn more about this mysterious fish!

Upside Down Catfish Stats

Scientific Name Synodontis nigriventris
Family Mochokidae
Genus Synodontis
Size of Fish 3 – 4 inches
Colors & Patterns Blotches of white and brown of varying shades
Diet Omnivore
Min. Tank Size 30 gallons
Temperature 72 – 82 F
pH 6 – 7.5
Hardness 4 – 15 dGH
Lifespan 15 years
Temperament Peaceful

Synodontis Nigriventris Background

The Synodontis nigriventris belongs to the Mochokidae family of catfish. There are about 200 species of Mochokidae catfish, but only seven of them spend most of their lives swimming in an inverted position. Among these topsy-turvy swimmers is the fish in question.

Ancient carvings have shown that people’s fascination with the Synodontis nigriventris goes back 4000 years ago. However, some scientists hypothesized that the species might have existed for much longer.

The common name “upside down fish” is an umbrella term used by ichthyologists to refer to all Mochokids that swim in an inverted position. Besides the Synodontis nigriventris, the following species may also be known by this common name:

  • Mystus leucophasis
  • Synodontis angelicus
  • Synodontis aterrima
  • Synodontis batensoda
  • Synodontis contracta
  • Synodontis nigrita

Of all seven species, the Synodontis nigriventris is the most popular fish in the hobby. But due to their resemblance, the S. nigriventris is often mistaken for other species.

– Where Do They Come From?

Central Africa is home to an immeasurable wealth of animal species, and the quizzical Synodontis nigriventris is no exception. Many of the Upside Down Catfish in the aquarium trade are collected from the Congo River basin throughout Kinshasa, Basonga, and Cameroon. There, the fish inhabit areas with lush foliage.

– Are They Getting Extinct?

Although the Synodontis nigriventris has lived a long time, its kind remains unclenched from the hands of extinction. The Upside Down Catfish possess a suite of adaptations that increase their survivability and make them tenacious in the face of threats.

Upside Down Catfish Appearance

The Synodontis nigriventris is one of those fish that you can’t help but look at twice. Besides its mind-boggling behavior, the upside-down catfish also exhibits physical features that leave you in awe.

– How Big Do Upside Down Catfish Get?

The Upside Down Catfish size is three inches for males and four inches for females. This length is the equivalent of a toilet paper roll. Compared to other species, these critters are on the smaller side of the spectrum.

– Distinct Features, Colors, and Patterns

Most sea creatures have an adaptation called countershading, which is the basis of camouflage in both predators and prey. In fish, such as the Great White Shark and Atlantic Bluefin Tuna case, it means the ventral side (bottom/belly) is a lighter color than the dorsal side (top). The purpose of this adaptation is to offset the effects of sunlight.

The Synodontis nigriventris, however, is different. Due to its reverse countershading, the species was thereby christened with the Latin name “nigriventris,” which implies having a black belly. More interestingly, the fish can darken their dorsal side so they can camouflage themselves no matter how they choose to swim.

As you can see in the picture, the fish flaunts a neutral color theme. Brown blotches of varying sizes and shades cover their entire body. For convenience, ichthyologists call them “blotched upside-down catfish.”

– How Can You Tell the Gender of an Upside Down Catfish?

Both sexes have large eyes, a forked tail, and three pairs of barbels similar to other members of the Mochokidae family. Females, however, are paler in color and can grow up to four inches in length. Males, on the other hand, look more saturated, and their size caps out around three inches.

Upside Down Catfish Behavior and Temperament

Often seeing your fish swimming upside down is a cause for alarm, but this isn’t the case for the Upside Down Catfish. As a matter of fact, it is an indicator that these fish are faring well.

– Decoding Synodontis Nigriventris Behavior

A lot of people are wondering, “Why do Upside Down Catfish swim upside down?” The reason why these fish swim the way they do remains a puzzle for future scientists to solve.

Even Ken Ohnishi and his team of researchers at Japan’s Medical University School of Medicine struggle to explain since there is nothing abnormal with the fish’s anatomy.

Regardless, the unusual orientation of the Synodontis nigriventris proved to be advantageous.

The whimsical catfish produce less wave drag when they are swimming in an upside-down position. In fluid dynamics, wave drag is the turbulence caused by friction. When a fish produces less wave drag, its movements are swift and smooth.

This allows the upside-down fish to do a better job of feeding insect larvae at the water surface. Unlike its right-side-up counterparts, the topsy-turvy swimmer doesn’t have to return to deeper water to rest.

– Are Upside-Down Catfish Active?

The nocturnal Upside Down Catfish kill daytime hours hiding underneath tank furnishings or behind plants. Once the sun sets and the buzzing noises fade away, the fish comes to life and becomes active at night! So don’t be surprised to see them swimming right-side-up. While these swim with finesse when upended, they can also swim like any other fish when searching for a tasty snack.

– Are Upside-Down Catfish Aggressive?

Despite their bizarre looks, the Upside Down Catfish is one of the best peace-loving residents you can add to a community aquarium. This species is here to prove that not all catfish are cross and cranky, as they can live in harmony with many freshwater fish.

However, they are somewhat shy and reclusive on their own. So you should keep them in a group of at least five to bring out their best behavior and keep stress at bay. But remember, these amicable catfish will not hesitate to eat juvenile fish if they can devour them whole.

– Are Upside Down Catfish Venomous?

No, they aren’t, but they can sting you with their barbs if you pick them up by hand. The pectoral and dorsal spines of the Upside Down Catfish can cause serious injury. Despite their peaceful disposition, these fish will kill their predators when worst comes to worst.

Adapt or Perish, the Upside Down Catfish’s Inexorable Imperative

Lauren Chapman, a biology professor at McGill University, conducted an experiment to understand how the upside down fish respond to hypoxia. She discovered that the fish’s strange way of swimming has allowed it to breathe at the water surface without difficulty.

Meanwhile, its right-side-up counterparts had to work harder for the same benefit. This ability is crucial for survival, especially when river systems become depleted of oxygen.

Besides their unconventional way of breathing and feeding, the Upside Down Catfish have a remarkable dark patch on their bellies. After all, they are called “nigriventris” for a reason.

But upon microscopic observation, there are melanophores on both ventral and dorsal skin. Melanophores are dermal pigment cells that produce and store melanin. These cells permit color change on both sides of the fish depending on their background.

Upside Down Catfish Tank Mates

This species has a pretty long list of potential tank mates, thanks to their amicable nature. But because Upside Down Catfish are small, it would be best to avoid large, dominant species that might view them as prey. These catfish will fight back when cornered and use their hard barbs to injure those trying to eat them.

Peaceful species, on the other hand, are fantastic to have regardless of their size. Angelfish, Denison Barbs, Small Elephant Fish, Congo Tetra, and African Butterfly Fish are excellent tankmates.

We also recommend adding a group of tight schooling fish to encourage these catfish to come out more often and help them feel more at ease in their new environment. The dither fish have to be adults; otherwise, you risk your fish from getting eaten.

Upside Down Catfish Care

It is no secret that the Upside Down Catfish lifespan can reach 15 years, but there is no telling if your fish can live that long in a captive setting. To increase the odds, secure a consistent, well-curated environment and a high-quality diet for your fish.

– Upside Down Catfish Diet

The Upside Down Catfish survives in the wild by feeding on insect larvae found on the water surface. After skimming the surface for insects, it heads back down to scavenge the bottom for scraps.

The fish also obtains satisfaction and nourishment from worms, small crustaceans, and microorganisms that adhere to submerged branches. When algae are available, these omnivores will nibble on them as well.

Sinking pellets and flakes can be given to these catfish in an aquarium environment. However, we recommend providing live food to stimulate their appetite and keep them in tiptop condition. Feed vegetable matter in the form of algae wafers and diced gourds.

– Water Parameters and Maintenance

The Upside Down Catfish prefer warm and moderately soft water. Your fish may tolerate slightly acidic water, but as much as possible, the pH reading should always stay as close to neutral. Aim for the following parameters:

  • Temperature: 72 – 82 F
  • pH: 6 – 7.5
  • Hardness: 4 -15 dGH
  • Water changes: 20 – 30 percent

Never skip out on performing partial water changes every week. Ammonia can accumulate in aquariums quite fast due to uneaten food, fish waste, and so forth.

– Health Risks

The Upside Down fish is a robust and highly adaptable species, but ammonia and nitrite spikes can be their kryptonite. Soaring ammonia levels can cause infected barbels that could impair their ability to navigate and locate food. Sadly, most catfish deteriorate quickly once their whisker-like sensory organs fall off.

Upside Down Catfish Tank Setup

Prepping up your aquarium is as important as keeping tabs on the water quality.

The goal here is to replicate the fish’s natural habitat and furnish the tank with accessories that will complement the behaviors of your fish as well as its fellow community residents.

– Tank Size

A well-furnished 30-gallon tank would make your Upside Down Catfish feel cozy. You are ill-advised to choose a smaller tank, although some hobbyists suggest a 20-gallon tank is already sufficient.

Maintaining the water parameters of a small tank is a lot more challenging than a large one. What’s more, these catfish love to roam around. The aquarium will provide enough swimming space for each, and you can also introduce a few compatible tank mates.

– Substrate

Upside down fish sometimes forage the bottom for morsels. Unlike plecos, these fish don’t have coarse scales to protect them, and their barbels are sensitive to boot. Therefore, there shouldn’t be sharp items in the tank. Opt for aquatic soil instead of gravel, but bear in mind that disturbing the substrate and plants may cloud the water in your tank.

– Plants and Decorations

The reason why we recommend aquatic soil is because it provides nutritional value. Live plants need nutrients to flourish, and although they absorb certain nutrients from the water, most of their nutrition is absorbed through the roots.

However, choosing live plants for your tank is not as simple as heading to your local fish store and select whatever is available. You’ll have to put as much thought into choosing your plants as you did for your tank decorations.

Here is a rundown of the best mid and background aquarium plants to get you started:

  • Water Wisteria
  • Amazon Fern
  • African Water Fern
  • Java Fern
  • Anubias
  • Cryptocoryne Beckettii
  • Dwarf Aquarium Lily

Since Upside Down Catfish love to hover around the waterline in hopes of getting a snack, you don’t want to overcrowd your aquarium with floaters.

– Equipment

There are gizmos and gadgets aplenty that offer incredible benefits for your tank but for now. You want to make sure you have these aquarium products.

Heater: Upside Down Catfish prefer warm water, ideally between 72 – 82 F. So we suggest you opt for a submersible heater to keep the temperature within the recommended range regardless of the climate. This type of heater doesn’t get exposed when performing partial water changes. Another advantage is that it keeps the temperature of the entire tank uniform.

Thermometer: To ensure the temperature is within the recommended range, you will need an aquarium thermometer as well.

Filter: Mechanical and biological filtration is crucial to prevent the water quality from degrading. You may choose between a powered filter (hang-on-back) and a canister filter. Each unit has its own set of pros and cons, but the most important consideration is that its flow rate can cycle four times the water volume of your aquarium. A 30-gallon tank, for example, requires a pump with a flow rate of 120 gph.

Upside Down Catfish Breeding

Upside Down Catfish are egg layers. In the wild, the wet season marks the beginning of the breeding period. However, breeding these catfish in an aquarium setting is a futile attempt. Until now, there are no official records of successful home breeding, although some hobbyists state otherwise. The majority of specimens sold in pet shops are either wild-caught or have been bred in hatcheries using hormones.

Conclusion

If you are looking for a pet fish out of the ordinary, I don’t think you could go wrong with the Upside Down Catfish.

  • At three to four inches, the Synodontis nigriventris is not a humongous species of catfish, which can be an advantage as you can pair them off with other peaceful tropical fish.
  • A 30-gallon aquarium filled with plants on the sides should help them feel cozy.
  • Poor water quality and lack of nourishment will turn their world upside down! Make your fish hale and hearty by keeping their habitat pristine. You can give them commercial fish feed as their staple diet, but don’t forget occasional servings of live fare.
  • Upside Down Catfish are undemanding, and they don’t have species-specific illnesses to boot. This makes them suitable for beginning aquarists. Although they appear to have swimming bladder disease, their anatomy states that they are normal.
  • Adding a group of adult dither fish should help encourage them to come out more and interact with their environment.

There are still unresolved mysteries of the Upside Down Catfish, but hopefully, this article has answered many of your questions.

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