Synodontis have an opening or series of openings called the axillary pore. It is located on the side of the body below the humeral process and before the pectoral fin spine. The exact function of the port is not known to scientists, although its presence has been observed in seven other catfish genera. Fish in the genus Acrochordonichthys have been observed to secrete a mucus with toxic properties from their axillary pore, but there is no scientific consensus as to the exact purpose of the secretion or the pore. S. petricola has a small axillary pore just below the humeral process. 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 S. petricola, and the back edges of the fins are white in color. The caudal fin has a black bar that runs from the base of each lobe to the top of the fin. The barbels are white. The maximum standard length of all known specimens is and a total length of . In general in Synodontis species, females tend to be slightly larger than males of the same age. Habitat and behavior In the wild, the species is endemic to Lake Tanganyika, which has a temperature range of , 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 . 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