When I got my first aquarium, I became slightly obsessed with oddball fish. I stocked my tank with kuhli loaches, glass catfish, twig catfish, and, maybe strangest of all, some upside-down catfish.
True to their name, upside-down catfish really do swim upside down most of the time – an unlikely evolutionary strategy that has many surprising benefits!
Upside-down cats are fairly easy to keep as long as a few essential requirements are met. Let’s find out how to best care for these highly unusual fish.
Upside-Down Catfish at a Glance
| Upside-Down Catfish Info | |
|---|---|
| Scientific Name | Synodontis nigriventris |
| Other Common Names | Blotched upside-down catfish, False upside down catfish, Dwarf upside down catfish, Mochokid catfish, Upside-down fish |
| Origin | Central Africa |
| Maximum Size | 4 inches |
| Temperament | Peaceful, but can eat smaller fish |
| Skill Level | Beginner to Intermediate |
| Minimum Tank Size | 30 gallons |
| Diet | Omnivore |
| Breeding | Egglayer |
| Lifespan | 7-15 years |
| Water pH | 6 to 7.5 |
| Water Hardness | 4 to 15 dGH |
| Temperature | 72 to 79°F (22 to 26°C) |
Species Overview
Clarification of Species
There are several species of catfish that are sometimes referred to as ‘Upside-down catfish’ due to their ability to swim upside down.
In this article, I’ll be focusing on the most popular member of this family: Synodontis nigriventris. Known to zoologists as the blotched upside-down catfish, this species spends most of its time swimming upside-down and is well-adapted to living in aquariums for several reasons.
Origin and Background
The blotched upside-down catfish hails from weedy river banks in the Congo Basin of Cameroon, the Democratic Republic of the Congo, and the Republic of the Congo.
In the wild, these freshwater fish swim together in large schools. Feeding upon insects, insect larvae, worms, algae, and vegetable matter, they spend most of their time swimming upside down, which allows them to surface feed, as well as browse the undersides of rocks and plants.
At the same time, these adaptable fish can also swim belly-down to feed on the bottom like other catfish species do.
Size and Appearance
Upside-down catfish are one of the smaller members of the catfish family. Only growing to around 4 inches or 10 cm in length, they’re classed as a dwarf catfish.
The name most commonly used by scientists ‘blotched upside-down catfish’ aptly describes this fish’s blotchy brown and black skin. The scientific name ‘nigriventris’ describes that this fish’s belly is darker than its back – an inverted evolutionary adaptation to help camouflage them from predatory birds.
Like other members of their family, they have four barbels that they use for feeling their way around the tank. These come in especially useful during the night when these fish are most active!
Their spiny dorsal fin can be locked in position and severely injure fish keepers who try to handle them or larger fish who attempt to eat or attack them!
Upside Down Catfish Care Guide
Tank Size
Upside-down catfish are inquisitive, active fish that like to explore both the bottom of the tank and the water’s surface. They also like to be kept in groups of at least five.
For these reasons, they should always be kept in an aquarium of at least 30 gallons and three feet in length.
A tank of at least 55 gallons allows you to stock the aquarium with several other tank mates, the most suitable of which we’ll discuss in a moment!
Tank Environment
Upside-down catfishes will be happiest when you replicate their natural habitat within your fish tank. In the wild, these curious fish reside along weedy riverbanks, often in shady areas underneath terrestrial vegetation.
Java fern, Java moss, Amazon Sword, Anacharis, Anubias, Crypts, and Vallisneria are all easy plants that will provide plenty of cover for upside-down catfish to swim among.
Upside-down catfish should also be offered plenty of rocky caves and pieces of driftwood to hide underneath, especially during the daytime when these semi-nocturnal fish like to rest undisturbed.
The best practice is to place some caves where they’ll receive strong water flow from the filter to provide the fish with adequate oxygenation.
Substrate
Some experts advise that upside-down catfish should only be kept in tanks with a soft, sandy substrate to protect their delicate barbles from getting damaged.
While sand may be superior to gravel in this way, it is also more difficult to clean and less conducive to vigorous plant growth.
If you do choose to use gravel, make sure it’s a smooth grade, without any sharp or jagged edges.
Lighting
Because upside-down catfish prefer subdued aquarium lighting, Floating plants like Amazon Frogbit and Water Sprite are useful to create dappled shade during the day.
Some aquarists have also discovered that ‘moonlight’ aquarium lights that simulate water lit up by a full moon are ideal for observing these fish after the main lights have gone out.
Water Temperature
Upside-down catfish are tropical fish that definitely require a reliable aquarium heater but will accept a wide range of water temperatures, from 72-79°F. This makes them compatible with most tropical aquarium fish.
Like other tropical species, upside-down catfish are sensitive to sudden changes in water temperature, so acclimatizing them properly in a new tank and avoiding temperature fluctuations is essential to avoid thermal shock.
Because upside-down catfish will often rest on the underside of aquarium equipment, it’s advised to place a guard around your fish tank heater to prevent them from burning themselves upon contact.
Water Parameters
Water chemistry is not so important with this fish as water quality.
Upside down catfish can tolerate any near neutral water chemistry. Try to keep tank water between pH 6-7.5, with a hardness of between 5- 20 dGH.
While fairly adaptable in terms of water chemistry, upside-down catfish demand clean water that’s well-oxygenated, so efficient filtration and frequent water changes are essential.
Filtration
An efficient aquarium filter is necessary for keeping any fish, but powerful filtration is especially important for river fish like this species that prefer a strong flow, high oxygen levels, and high water quality to thrive.
Hang-on-back filters and internal power filters are good options for small-medium-sized tanks. For larger aquariums, consider a canister filter.
You can effectively increase the dissolved oxygen levels in your water by increasing water surface agitation. Aquarium spray bars and lily pipes are helpful accessories to do this.
Feeding
Upside-down catfish are renowned for their voracious appetite and also their tendency to overfeed and become bloated! Feeding limited quantities of a well-balanced diet of sinking foods is therefore a top priority.
Unfussy in their eating habits, upside-down catfish will accept almost any type of sinking tropical fish food such as catfish pellets.
Because they’re primarily carnivorous fish in the wild, however, dried fish foods should always be supplemented with high protein fresh and frozen foods such as bloodworms, tubifex worms, daphnia, brine shrimp, and especially mosquito larvae.
Occasional helpings of vegetable foods like blanched spinach, dandelion leaves, nori flakes, spirulina wafers, or algae wafers may also be appreciated.
Because they eat some types of algae and uneaten food from the bottom of the tank, upside-down cats could be considered part of the tank’s ‘clean-up crew’.
As usual, feed your fish twice a day, with no more than they can eat in 2 minutes. Even if they seem hungry, be careful not to feed too much!
Temperament
Upside-down catfish are generally peaceful fish that largely ignore their tank mates. It must be remembered, though, that at 4 inches long, these carnivorous fish will eat anything they can fit in their mouths!
Very small fish, fish fry, and shrimp, therefore, could easily get eaten by upside-down catfish that will often go looking for food at night when other fish are sleeping.
Like other catfish, upside-down catfish species have also been noted for eating aquarium snails on some occasions.
Behavior
The behavior of upside-down catfish will vary considerably depending on how comfortable they feel in your aquarium.
When kept in groups of 4 or more fish, in a tank with peaceful tank mates, upside-down catfish may appear quite bold, unafraid to swim in open water and feed from the surface.
When kept in smaller groups or tanks with aggressive fish, however, they can become very shy fish.
In my younger years, I made the mistake of keeping just a pair of upside-down cats. Feeling under-confident, they’d usually hide for the entire day, making it hard for me to know if they were still alive! I’d typically only catch a glimpse of one after turning the lights off.
The moral of the story is always to keep these social fish in groups of at least four, with five to seven fish being even better.
Compatible Tank Mates
As a fairly peaceful species, upside-down catfish can be kept in community tanks with a wide range of other medium-sized, relatively peaceful tank mates.
Larger tetras, danios, rasboras, livebearers, barbs, gouramis, and rainbow fish all make good companions. Delicate and tiny fish like betta fish and Medaka rice fish are best avoided.
While some people have suggested peaceful cichlids like angelfish, ram cichlids, and kribensis, tensions could arise after spawning when cichlids will try to dominate the bottom of the tank, and upside down catfish would likely try to eat the fry.
Health and Disease
Upside-down catfish demand excellent water quality and may develop health problems and illnesses if water conditions deteriorate or they become stressed.
Ich, velvet, and flukes are all common parasitic diseases that can lie dormant in an aquarium for years until a weakened fish or very poor water quality offers them a chance to strike.
Similarly, bacterial and fungal infections like columnaris and water molds only tend to affect fish that are already in a vulnerable state.
Keeping upside-down catfish in groups of 4 or more, with plenty of hiding places in a clean tank, is therefore the best defense against stress and unnecessary diseases.
Sexual Dimorphism
Male upside-down catfish are smaller than females and have a darker body color. As females reach sexual maturity, they’ll develop a larger, plump shape, and a lighter color.
Breeding
Upside down catfish are only thought to have been bred in captivity on a few occasions. Because they’d naturally migrate to floodplains to spawn, attempting to breed them in a home aquarium is extremely difficult.
Definitely a project left only to the most adventurous fish keepers with experience in breeding easier catfish like peppered cories or bristlenose plecos.
Lifespan
Long-lived fish, upside-down catfish have been known to exceed 15 years old in captivity.
For them to reach their maximum lifespan, their diet, water quality, and aquarium environment must all be of the highest order.
Strange Fact – Upside-Down Catfish Squeaking!
When I kept upside-down catfish in my bedroom, I used to hear strange squeaking sounds coming from the tank in the middle of the night.
Those were the days before you could quickly solve a mystery with Google, and since none of my aquarium books mentioned it, it remained a mystery that fish could be making the sound.
I did suspect the upside-down catfish, mostly because it was the strangest fish in my tank! It turns out that members of the Synodontis family make the squeaking sound by rubbing the spines of their pectoral fins against the ridges on their body, much like we can make a sound by rubbing a fingernail against a plastic comb.
According to scientific studies, these sounds are produced to ward off potential predators or during conflicts with other fish.
Tank Maintenance
Some top tips for keeping your upside-down catfish in tip-top condition!
- Feed upside-down catfish a diverse, healthy diet that includes regular additions of live or frozen foods. Avoid overfeeding!
- Install a good filter with a strong flow and clean it every 2-3 weeks.
- Vacuum your substrate and make partial water changes of 15-35% every 1-2 weeks with treated water of matching temperature.
- Get yourself a reliable heater and thermometer. Make daily checks to ensure the temperature is within the ideal range for all of your fish.
- Observe your fish closely every day to ensure they are in good health and interacting peacefully with each other.
- Test your aquarium’s water at least once a month or any time your fish seem unwell.
Buying Guide
Upside-down catfish are fairly popular aquarium fish and can be found in most larger aquarium stores.
If you’re buying your fish from a store, only choose active individuals, with bright colors, shiny eyes, and healthy-looking fins. If you’re buying online, always check reviews to ensure the site’s integrity.
Expect to pay between $10-25 for an upside-down catfish in 2023.
Final Thoughts
Upside-down catfish are an intriguing oddball fish for community aquariums.
While upside-down catfish are fairly easy to keep, they must be kept in groups of at least 4, in clean water, and away from tiny fish that they are likely to eat!