Synodontis petricola, known as the Cuckoo Catfish or the Pygmy Leopard Catfish, is a species of upside-down catfish endemic to Burundi, Zambia, the Democratic Republic of the Congo, and Tanzania where it is only known from Lake Tanganyika. species name «petricola» is derived from a combination of the Latin petra, meaning stone or rock, and the Latin cola, meaning inhabitant. This refers to the rocky environment where this species is found.
In the wild, the species is endemic to Lake Tanganyika, which has a temperature range of 23 to 26 °C (73 to 79 °F), and an approximate pH of 8.5 – 9, and dH range of 4 – 15. It inhabits rocky shorelines in the littoral zone, to a maximum depth of 30 metres. The reproductive habits of most of the species of Synodontis are not known, beyond some instances of obtaining egg counts from gravid females. Spawning likely occurs during the flooding season between July and October, and pairs swim in unison during spawning. Juveniles appear to be carnivorous, feeding on water mites, seed shrimp, and insect larvae. Adults feed on algae scraped from rocks as well as small invertebrates. The growth rate is rapid in the first year, then slows down as the fish age. The pygmy leopard catfish practices brood parasitism. It lives among rock piles frequented by various species of Mauna: small African cichlids. Courtship behaviour culminates with the female sucking sperm from the male’s cloaca. She brings the sperm through her digestive tract to her cloaca, where her eggs meet the sperm. She then rushes into the nest of a cichlid, devours the eggs, and deposits her own. The cichlids then raise the catfish as their own.
Like all members of the genus Synodontis, Synodontis petricola has a strong, bony head capsule that extends back as far as the first spine of the dorsal fin. The head contains a distinct narrow, bony external protrusion called a humeral process. The shape and size of the humeral process help to identify the species. In Synodontis petricola, the humeral process is triangular, rough, and is covered in many small, thin papillae.
The fish has three pairs of barbels. The maxillary barbels are located on the upper jaw, and two pairs of mandibular barbels are on the lower jaw. The maxillary barbel has a narrow membrane attached near the base and is straight without any branches.
The skin of Synodontis petricola has a large number of tiny vertical skin folds. The exact purpose of the skin folds is not known but is a characteristic of the species of Syndontis that are endemic to Lake Tanganyika. The front edges of the dorsal fins and the pectoral fins of the Syntontis species are hardened into stiff spines.
The back of the fish is yellowish to copper-brown and is covered with large, irregularly-shaped black spots. In juveniles, these spots can appear larger and sometimes intersect. The underside of the fish is lighter, with small, irregularly shaped spots. Most of the species of Synodontis of Lake Tanganyika have a recognizable pattern consisting of dark triangles at the bases of all of the rayed fins, present in Synodontis petricola, and the back edges of the fins are white in colour. The caudal fin has a black bar that runs from the base of each lobe to the top of the fin.
The maximum standard length of all known specimens is 11.5 centimetres (4.5 in) and a total length of 13.5 centimetres (5.3 in). In general, in the Synodontis species, females tend to be slightly larger than males of the same age.