Aquarist Atlas
↑ Collection form of Petrochromis polyodon

Petrochromis polyodon "Mtoto"

Mtoto — m-TOH-toh (approx.)

The fish

How this cichlid is built, and everything about how it lives, eats and breeds, is shared with the species — this page doesn't repeat it.

Read the full Petrochromis polyodon account →

Specific to Mtoto

  • Collection locality & coordinates
  • Local coloration — best judged from the living-fish photo
  • Kept as a single-provenance line, never crossed with other collection points

Care facts below are the species' — shared with Petrochromis polyodon.

IUCNENDANGERED · 2025
CARESNOT LISTED
Scientific size8.3 in21 cm total length
Temperature73–79 °F23–26 °C
pH7.2–8.5alkaline
Depth0–23 ft0–7 m
DietHerbivore; scrapes epilithic algae (aufwuchs — diatoms, unicellular algae, fine organic film) from rock surfaces using dense comb-like tricuspid teeth
Breedingmaternal mouthbrooderFemales 12.6–14.1 cm SL brood eggs from cleavage stage to free-swimming larvae ~2.83 cm
Sexual dimorphismYesMales generally larger; dominant territorial males develop stronger coloration including blue iridescence on head and unpaired fins; females and subordinate fish remain plainer
PhotographsSee photosGoogle Images →

The Mtoto population

Petrochromis polyodon "Mtoto" is the Mtoto population of Petrochromis polyodon, a geographic colour form from the Democratic Republic of the Congo coast of Lake Tanganyika in the north-central part of the lake. It is the same species as Petrochromis polyodon, distinguished by its collection locality and local coloration; aquarists keep and breed it as a discrete, provenance-labelled line.

Colour reference: living Mtoto fish at tanganyika.si →

About the species

Petrochromis polyodon is the type species of Petrochromis, a genus of rock-grazing cichlids found nowhere on Earth but Lake Tanganyika, and it earns its keep by scraping a living off stone. A mouthful of dozens of fine, comb-like teeth lets it brush diatoms and algal filaments from the rock face the way a wire brush works a grill, and on the lake's sunlit reefs it is one of the most committed and aggressive grazers of them all. Reaching about 8 inches (21 cm), it holds a feeding territory it will defend against almost anything, packs the same intensity into a tank, and is, as of a 2025 reassessment, now formally listed as Endangered — a status that says as much about its shallow, sediment-prone home as about the fish itself.

Full Petrochromis polyodon account →

Sources

  1. tanganyika.si — Petrochromis polyodon "Mtoto"
  2. Eschmeyer's Catalog of Fishes — Petrochromis polyodon Boulenger, 1898
  3. FishBase — Petrochromis polyodon (Boulenger, 1898)
  4. FishBase — Food and Feeding Habits Summary, Petrochromis polyodon
  5. GBIF — Petrochromis polyodon (Boulenger, 1898)
  6. Boulenger (1898), Proc. Zool. Soc. London — Report on the fishes recently obtained by Mr. J. E. S. Moore in Lake Tanganyika (original description; via CRC reference archive)