Petrotilapia micrognathos

Petrotilapia micrognathos is a species in the large, algae-specialised Petrotilapia genus from Lake Malawi, distinguished from other Petrotilapia by its relatively smaller jaw ('micrognathos' meaning small jaw). Males are vividly blue to blue-grey with dark barring. Females are cryptically brownish, typical of the genus.

All Petrotilapia possess specialised tricuspid teeth used to scrape dense Aufwuchs algae growth from rock surfaces — a dietary specialisation so extreme that any significant introduction of animal protein into the diet consistently triggers Malawi bloat, often with fatal results. P. micrognathos is a large, dominant species requiring a minimum 250 L tank and extensive rockwork. Only one male should be kept per tank unless the system is very large. Females are maternal mouthbrooders incubating eggs and fry for 21–28 days. Dedicated to experienced keepers.

Water: 24–28°C, pH 7.8–8.5, hard (GH 10–25, KH 6–15); powerful filtration and consistent water changes are mandatory. Tank: 250 L minimum; extensive rock structures; one dominant male per tank to prevent fatal male conflict. Feeding: Exclusively algae — spirulina flake, algae pellets, blanched zucchini; even occasional bloodworm causes bloat risk. Breeding: Maternal mouthbrooder; female holds 21–28 days; isolate to a quiet recovery tank during brooding. Compatibility: Petrotilapia-appropriate tanks with other large, robust mbuna; avoid peaceful cichlids.