Cuckoo catfish

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: sand.

Behavior

Plant interaction: plant safe.

Typically wild-caught; acclimate slowly.

Feeding

Sinking pellets, sinking wafers, frozen bloodworm, frozen brine shrimp, frozen mysis, and live food (blackworms, brine shrimp). They forage after dark, methodically working over the substrate and rock surfaces. In cichlid tanks, they eat leftovers from the cichlids' feeding and supplement with whatever they find on the bottom. Dedicated feeding after lights-out ensures they get enough. Algae wafers are accepted but they're not herbivores; protein-based sinking food is the better staple. Feed once daily, timed to lights-out.

Nocturnal feeder; drop food after lights out.

Compatibility

• Ideal catfish companion for Lake Malawi and Lake Tanganyika cichlid tanks. The species evolved alongside rift lake cichlids and fits into their social dynamics without conflict.
• Nocturnal and reclusive during the day. Groups of 4+ are less shy, but even in groups they spend most of daylight hours wedged inside rock crevices. Activity peaks at dusk and through the night.
• Peaceful toward other fish but will eat very small species and fry. In a cichlid tank, this is a feature: they clean up stray fry and help control overpopulation from prolific mouthbrooders.
• Often confused with Synodontis lucipinnis, which is similar in appearance and also from Lake Tanganyika. Both species are sold as 'dwarf petricola' or 'pygmy synodontis' in stores, and the care is identical.

Origin and habitat

Endemic to Lake Tanganyika, found in Burundi, Zambia, the Democratic Republic of the Congo, and Tanzania. Described by Matthes in 1959. A member of the family Mochokidae (upside-down catfishes). Also known as the pygmy leopard catfish. Inhabits rocky shorelines in the littoral zone, to a maximum depth of about 30 m. Lake Tanganyika water conditions: temperature 23-26°C, pH roughly 8.5-9, dH 4-15. This alkaline water tolerance makes S. petricola a natural companion for rift lake cichlid tanks. Reaches a maximum standard length of about 11.5 cm (total length 13.5 cm); the fish commonly sold as "dwarf petricola" may be S. lucipinnis, a closely related species that grows slightly smaller (up to about 10 cm TL) and is difficult to distinguish from S. petricola. S. lucipinnis can be told apart by the lack of an axillary pore and the presence of light-colored windows at the bases of the rayed fins. White dorsal and pectoral fin spines are distinctive; body has dark spots on a lighter background with white-edged fins. Practices brood parasitism: females deposit their eggs in the nests of mouthbrooding cichlids after consuming the cichlid's eggs. Juveniles are carnivorous, feeding on water mites, seed shrimp, and insect larvae; adults also graze algae from rocks. IUCN Least Concern.

Breeding

Brood parasite in the wild, using one of the most remarkable reproductive strategies in freshwater fish. In Lake Tanganyika, S. petricola times its spawning to coincide with mouthbrooding cichlids (particularly Cyphotilapia frontosa and various Tropheus species). When the cichlid female is collecting her newly laid eggs in her mouth, the catfish darts in and releases its own eggs among them. The cichlid female unknowingly picks up the catfish eggs and incubates them alongside her own. The catfish fry hatch first and eat the cichlid eggs and fry inside the mother's mouth. In the aquarium, this behavior can be replicated in tanks housing mouthbrooding cichlids: the catfish will parasitize any mouthbrooder that's spawning. Outside the brood parasitism context, S. petricola has been bred by conditioning groups in large tanks and allowing them to spawn conventionally among rocks. Eggs are deposited in rock crevices and hatch without cichlid incubation, but survival rates are lower and the process is inconsistent.

Common problems

Shyness is the main behavioral concern. In tanks without enough rock cover, they hide constantly and stress out. Provide stacked rocks with narrow crevices sized for the catfish to wedge into. Ich is uncommon in established rift lake tanks but can appear during transport stress; standard treatment works. The hard alkaline water that these fish require is the opposite of what most tropical fish disease treatments assume, so check medication compatibility with high-pH water. Spinal deformities occasionally appear in commercially bred specimens, likely from inbreeding. Avoid fish with visible spinal curvature. Confusion with S. multipunctatus leads to care mistakes: S. multipunctatus reaches 20 cm and is more aggressive, so buying a mislabeled fish means ending up with a larger catfish than expected.

Bioload

Further reading

• How to cycle a fish tank
• Stocking ideas by tank size