Lake Malawi, measured in two numbers
Peacock cichlids — the Aulonocara group — live in Lake Malawi, a vast African rift lake whose water is warm, hard, and distinctly alkaline, and barely changes from season to season. The aquarium translation is about 76 to 82 degrees Fahrenheit and a pH of roughly 7.6 to 8.6. That stability is the point: a lake that large does not swing, and peacocks evolved expecting the same water every day of their lives.
The commonest peacock mistake is housing them in ordinary community conditions near neutral pH because the fish initially seem fine. Over months in soft, neutral water, colours mute, finnage loses its edge, and low-grade infections find footholds. The fish were not hardy; they were spending reserves.
Building and holding alkalinity honestly
If your tap water is naturally hard and alkaline, peacock keeping is easy — test it, and you may already be at pH 7.8 or above. Soft-water households have real work to do: crushed coral or aragonite in the filter or substrate dissolves slowly and pushes both hardness and pH upward while buffering them there, which is far steadier than dosing powders that spike and fade. Whichever route you take, change one thing and then measure across a week before changing another.
Replacement water is where Malawi tanks quietly fail. A keeper who buffers the display tank but refills from a soft tap supply dilutes the alkalinity with every change, and the pH saws downward month by month. Condition the change water to match the tank — same approximate pH, same temperature — in the bucket, before it goes in. Large, well-matched changes suit peacocks well; their lake is clean, and nitrate should stay low.
Temperature and the male colour question
Warmth in the upper seventies supports the metabolism behind a male peacock's display colour — the blues, yellows, and reds that make the group famous. Run cool, and males hold a duller, female-like wash. Run the social side wrong, though, and no temperature rescues colour: a subordinate male in a tank with a dominant one suppresses his dress as camouflage, in perfect water. Read colour as a combined report on chemistry, rank, and health, in that order of checking.
Females and juveniles stay silvery-brown by design, sifting sand for invertebrates. Sand matters chemically as well as behaviourally — a sand bed of aragonite contributes to the buffer, while inert dark gravel does not. Peacocks dig and rearrange, so rockwork should sit on the glass or egg-crate, not balanced on substrate the fish will undermine while following their instincts.
Tankmates must sign the same contract
Everything in a peacock tank must want Malawi water: other Aulonocara, compatible Malawi haps, and hardy alkaline-water catfish are the usual companions. Plecos and tetras from soft Amazon water are the classic bad pairing — one side of that tank is always living in the wrong lake.
Quarantine deserves the same chemistry discipline. A hospital tank at neutral pH may be worse for a sick peacock than the display water it came from; match the Malawi recipe there too, so treatment is not compounded by acclimation stress in both directions.
Two tanks, two recipes, no confusion
Households with a Malawi setup often also keep a soft-water community tank, and change day is when the recipes cross: Malawi water in the tetra tank, soft water in the peacocks'. Labelling which profile carries which targets — alkaline and warm for the peacocks, with the buffer method written out — removes the guesswork for anyone helping. That separation is a natural use of KinsLe Family Sharing, where the peacock tank's Lake Malawi numbers live in its own profile, distinct from every other tank in the house.