The Ocellated Synodontis is a catfish with plenty of spots, and sometimes very big spots!

The Ocellated Synodontis Synodontis ocellifer certainly has plenty of spots. Its scientific names originate from Greek. The genus name, a combination of “syn” meaning “together” and “odontos” meaning “tooth”, describes their closely spaced mouth. The species name, however, is the telltale designation of this particular fish. The Greek word “ocellifer” means “little eyes” or “eye-like spot”, which aptly describes the dark spots on its body.

This fish is also commonly known as the Large-spot Catfish. There are several color forms including black, tan, and yellow. Some have color in the finnage, while others have almost no color other than their large spots. The large spot variety is usually thought to be the most attractive of the color forms, and though it used to be quite rare it is now fairly common.

Synodontis catfishes are members of the Mochicidae family. As a group they are commonly called Naked Catfish, Upside-Down Catfish, and Squeaker Catfish, with each name reflecting a characteristic aspect of their makeup. The term “Naked Catfish” comes from the lack of scales, scutes or any other kind of body protection. They have been dubbed with the name “Squeaker Catfish” because they are some of the most vocal catfish. Contrary to popular belief, most Synodontus don’t swim upside down, yet they became known as Upside-Down Catfish due to the popularity of the first-kept member of the genus, Synodontis nigriventis.

Although this Synodontis (like most of this genus) gets rather large in the wild, reaching up to 19″ (20 cm), in the home aquarium they rarely exceed 10″ (25.4 cm). It is an excellent addition to a large community aquarium of 50 gallons or more. It is a very peaceful bottom scavenger that appreciates having several hiding places. They are more reclusive during the day and will be most active and feed in the evenings.

Large-spot catfish are fairly hardy and are not difficult to keep in a well maintained environment, making them quite suitable for beginning aquarists. Provide a soft substrate along with a decor of rocks and wood that create plenty of caves and crevices for hiding and places of retreat. They will also appreciate some surface floating plants to help reduce the amount of daylight in the aquarium. Other plants are fine, but not necessary.

Take great caution when transporting this fish. The spines on the pectoral fins of this fish have serrated edges. It can easily be injured while netting because these spines can get caught in netting materials. The spines can also pierce most plastic bags. Transport containers of doubled up heavy duty plastic bags can work, but hard plastic or glass containers are the safest bets.

For Information on keeping freshwater fish, see:
Freshwater Aquarium Guide: Aquarium Setup and Care

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Siluriformes
  • Family: Mochokidae
  • Genus: Synodontis
  • Species: ocellifer
Large-spot Catfish – Quick Aquarium Care
  • Aquarist Experience Level: Beginner
  • Size of fish – inches: 19.3 inches (49.00 cm)
  • Minimum Tank Size: 50 gal (189 L)
  • Temperament: Peaceful
  • Aquarium Hardiness: Moderately hardy
  • Temperature: 73.0 to 82.0° F (22.8 to 27.8&deg C)
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Habitat: Distribution / Background

The Ocellated Synodontis Synodontis ocellifer was described by Boulenger in 1900. They are found in various West and Central African river systems, and occur in river basins of the Chad, Senegal, Gambia, Volta, Niger, and the Benue. They are listed on the UCN Red List of Endangered species as Least Concern (LC) because this species has a wide distribution with no major, widespread threats identified.

Another common name this species is known by is Large-spot Catfish. The Synodontis catfish belong to the Mochicidae family, and consists of over 151 different species. As a group they are commonly called Naked Catfish, Upside-Down Catfish, and Squeaker Catfish. The term “Naked Catfish” comes from the lack of scales, scutes or any other kind of body protection. The name “Squeaker Catfish” comes from their ability to make a squeaking sound with their pectoral fins. They are some of the most vocal catfish and will generally “squeak” when they are frightened, angry, or are disturbed. Contrary to popular belief, most Synodontus don’t swim upside down, yet they became known as Upside-Down Catfish due to the popularity of the first-kept member of the genus, Synodontis nigriventis.

The Ocellated Synodontis inhabit slow moving streams and backwaters. These are a peaceful fish that will be found in schools as juveniles, but as adults they prefer a solitary life. They are very quiet and still during the daytime, then become active in the evening hours and at night, scavenging for food items.

They mostly eat plant matter and algae, but will also consume dead fish, worms, and other proteins. Foods they have been reported to consume in the wild include zoobenthos, mollusks, bivalves, oysters, terrestrial insects, detritus, debris, benthic algae/weeds, benthic crustaceans, zooplankton, and other planktonic invertebrates.

  • Scientific Name: Synodontis ocellifer
  • Social Grouping: Solitary – They will school when young, but are solitary as adults.
  • IUCN Red List: LC – Least Concern


The Synodontis ocellifer have a cylindrical body with a flattened belly and a large head with small eyes. As with all in its genus, the Large-spot catfish have an armor-like hardened head cap that is attached to the humeral process behind the gill opening pointed towards the posterior. The mouth of this fish is S-shaped with a movable lower jaw and cone-shaped teeth in their upper jaw. Very important to this fish are its maxillary barbels used to navigate and locate food. There are also two pairs of mandibular barbels and nodes attached.

The dorsal and pectoral fins have hard serrated spines. They can actually use their pectoral spines to produce audible sounds when disturbed by rubbing them against their pectoral girdle. The caudal fin is forked.

It has a yellowish-brown body with black spots all over its body. There are several color forms including black, tan, and yellow. Some specimens have lighter background coloration or minimal spotting. Some have color in the finnage, while others have almost no color other than their large spots.

This species can be confused with other similar looking species of Synodontis. The characteristic to look for when comparing with other similar spotted species is the adipose fin (small fin located between the dorsal and caudal fin). In this species the adipose fin is very long, extending from just past the base of the tail to just before the caudal fin.

  • Size of fish – inches: 19.3 inches (49.00 cm) – They will generally not exceed 10 inches in the home aquarium, though fish reaching lengths of 19 inches have been reported in the wild.
  • Lifespan: 20 years

Fish Keeping Difficulty

The Ocellated Synodontis is not a difficult fish to care for and will be great for a beginner fish keeper. However it does need a good sized tank of 50 gallons or more, and as juveniles are much more pH sensitive then adults, adult fish are the best choice for beginners. It has the characteristic sharp spines on its dorsal fin and so should be transported using a glass or plastic container rather than a net.

They require clean water that is high in oxygen and a good supply of food on the bottom of the tank. An undergravel filter system will work best, it will maintain clean water and ensure the entire tank is highly oxygenated. A little salt can be added to their water to aid in disease prevention.

These fish do a great job keeping the bottom cleaned of food and debris, making them little living vacuums. However, these fish are known to die from overeating so take care not to over feed. It can sometimes be difficult to make sure this fish is getting the proper nutrients, make sure to vary their diet.

  • Aquarium Hardiness: Moderately hardy – This fish is hardy if the tank is well kept.
  • Aquarist Experience Level: Beginner

Foods and Feeding

The Ocellated Synodontis are omnivores and are most unfussy in terms of feeding. In the wild they will feed on just about everything. In the aquarium they will generally eat all kinds of live, frozen, and prepared foods. To keep a good balance give them high quality sinking pellets everyday, along with freeze-dried bloodworms and tubifex, and a good quality flake food. Also feed brine shrimp (either live or frozen) or blood worms as a regular treat. Make sure to provide foods with vegetables for balanced nutrition. If the tank is not established adding algae wafers to the tank is a good substitute. They will also relishes vegetable foods such as shelled peas and cucumbers.

  • Diet Type: Omnivore – Although omnivorous this fish prefers a greater protein component to its diet. Frequently treating with live foods such as bloodworms or brine shrimp is highly advised.
  • Flake Food: Yes
  • Tablet / Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Some of Diet
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day

Aquarium Care

These fish need a lot of oxygen and weekly water changes are important to keep this fish happy. Water changes of 30% weekly are necessary. They do best with an undergravel filter system as it will help keep the water highly oxygenated. If there is not enough oxygen, these fish will swim to the surface and gulp air and then swim back down. If this is a common occurrence, it is a good indicator that the water quality is deteriorating.

  • Water Changes: Weekly – Do water changes of 30% weekly to keep these fish healthy.

Aquarium Setup

The Ocellated Synodontis are good sized fish, so need a minimum sized tank of 50 gallons, with 75 gallons or more being better. Provide a setup with many hiding places as they will spend much of their time hidden under driftwood or in caves during the day. Driftwood, Large twisted roots, and rocks forming caves make great places for retreat. This will also help shelter their fry if you get lucky and they decide to breed. Driftwood is very necessary to these fish, it not only acts as a hiding place but it will also be chewed on it and they get some nutrition out of it.

Floating vegetation on the surface will help reduce the amount of light, which will also be appreciated. Other plants can be included but are not essential. Use a smooth substrate with an undergravel filter to ensure the water stays properly aerated. The use of a powerheads will aid in keeping the tank aerated. To get the most enjoyment out of this keeping this fish you can use Moonlight LEDs for nighttime viewing.

  • Minimum Tank Size: 50 gal (189 L) – A minimum sized tank of at least 50 gallons is needed, 75 gallons or more is better..
  • Suitable for Nano Tank: No
  • Substrate Type: Any – As bottom scavengers, a smooth substrate is best.
  • Lighting Needs: Moderate – normal lighting – They do prefer a dim tank during the day, floating plants on the surface to help to subdue the light. Moonlight LEDs can be added for nighttime viewing.
  • Temperature: 73.0 to 82.0° F (22.8 to 27.8&deg C)
  • Range ph: 6.2-7.5
  • Hardness Range: 2 – 15 dGH
  • Brackish: No
  • Water Movement: Moderate
  • Water Region: Bottom

Social Behaviors

The Synodontis Ocellifer are peaceful bottom scavengers. They are generally a good community fish and can be kept with most tankmates, with the exception of fish that are so small they could be considered food. However they are not recommended for the general community due to their adult size. Ideal tankmates include Alestiid tetras, robust cichlids (particularly West African species), Mormyrids, Knifefish, Gouramis and larger rasboras and barbs.

This fish tends to become slightly territorial as it matures, especially towards other Synodontis catfish. However any aggression is usually far less pronounced than in some other members of the genus. It can be kept singly or maintained in a small group in a suitably sized aquarium, provided each fish is given a refuge to call home.

  • Venomous: No
  • Temperament: Peaceful
  • Compatible with:
    • Same species – conspecifics: Yes – Yes – More than one can be kept successfully in the same aquarium as long as it is large enough and each fish has its own place of refuge. They can be kept as single specimens as well.
    • Peaceful fish (): Safe
    • Semi-Aggressive (): Safe
    • Aggressive (): Monitor – Many semi-aggressive and aggressive fish will not bother the nocturnal Synodontis catfish.
    • Large Semi-Aggressive (): Monitor
    • Large Aggressive, Predatory (): Monitor
    • Safe
    • Shrimps, Crabs, Snails: Safe – not aggressive
    • Plants: Safe

Sex: Sexual differences

Sexing these fish is not an easy task. Normally the females are much plumper then the males. To be certain the genital papilae can be examined. Hold the fish with the dorsal fin in between your fingers making sure not the puncture your skin. Turn the fish over and carefully pull the caudal fin to expose the genital area. Males will have pointed ridged papillae and the sperm duct can be seen on the caudal side. Females papillae is round with oviduct on the opposite side then the males.

Breeding / Reproduction

The Synodontis Ocellifer has not been bred in captivity under normal conditions, nor in the aquarium. In the wild this species are egg scatterers and exhibit no parental care. They breed where there is seasonal flooding that provides a rich assortment of micro-organisms.

With the exception of the Upside-Down Catfish, Synodontis nigriventis and possibly the Black Synodontis, Synodontis nigrita, most of the catfish in this genus have not been bred in captivity. Nutrition is very important for their breeding and some of the nutritional substances they get from their natural diet, notably snails and insect larvae, are not always readily available as fish foods.

Commercial fish farms in Europe have successful bred these fish with the use of hormone injections. Many of the young fish available in there market have been produced in this way. A number of hybrids of this species have reportedly also been appearing there in recent years. For information on the breeding of catfish in the aquarium, see: Breeding Freshwater Fish: Catfish.

  • Ease of Breeding: Unknown – Breeding has been accomplished by the use of hormone injections in Europe.

Fish Diseases

The Synodontis Ocellifer are hardy and disease is not usually a problem in a well maintained aquarium. There is no guarantee that you won’t have to deal with health problems or disease, but catfish are very resilient. The most common problem that happens to this fish are injuries from netting and transportation. Take great caution when catching and removing this fish. High nitrate levels can also cause these catfish to develop infected barbels; this makes it difficult for them to navigate and eat normally. Maintain nitrate levels below 20 ppm through regular water changes.

Because they are a scaleless fish, catfish can be treated with pimafix or melafix but should not be treated with potassium permanganate or copper based medications. Malachite green or formalin can be used at one half to one fourth the recommended dosage. Take care when treating disease as the Synodontis Ocellifer is extremely sensitive to medications.

The best way to proactively prevent disease is to give your fish the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. A stressed fish will is more likely to acquire disease. Anything you add to your tank can bring disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria. Properly clean or quarantine anything that you add to an established tank so not to add new diseases to the tank. For information about fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.


The Ocellated Synodontis Synodontis ocellifer is available from time to time. The large spot variety used to be quite rare but is fairly common today.