Taxonomy & naming
The kotsovato was described by the French ichthyologist Jacques Arnoult in 1960, as Paretroplus kieneri, in the Bulletin du Muséum National d'Histoire Naturelle. The type locality is Lake Kinkony in northwestern Madagascar; the holotype (MNHN 1960-0580) and a single paratype (MNHN 1960-0581) are lodged in the Paris museum. The name has stood unchallenged ever since — there are no junior synonyms — and the species remains valid as originally combined. The genus Paretroplus was erected by Pieter Bleeker in 1868 for the deep-bodied cichlids of Madagascar, and modern work places it, together with the Indian/Sri Lankan Etroplus and the brackish-water Pseudetroplus, in the subfamily Etroplinae: a small, ancient lineage whose split from the rest of the cichlid family traces to the breakup of Gondwana. John Sparks' comprehensive 2008 revision of the subfamily (Bulletin of the American Museum of Natural History 314) redescribed Paretroplus kieneri and resolved its relationships in detail, recovering it as the sister species of Paretroplus gymnopreopercularis, a narrowly distributed relative of the Mahavavy drainage. Within the genus kieneri belongs to a group of comparatively shallow-bodied, mottled species set apart from the tall, banded dambas such as P. maculatus and Paretroplus menarambo.
Morphology
Paretroplus kieneri is the smallest of the dambas: FishBase records a maximum of about 6.5 in standard length, and hobby accounts give roughly 6–8 in total length, with most adults near 6.5 in (about six inches). It is also the most shallow-bodied member of an otherwise deep-bodied, surgeonfish-like genus — an ovoid rather than disc-shaped fish. The fin counts run to 18–20 dorsal spines and 13–15 soft rays, with 9–11 anal spines and 11–12 anal soft rays. Two features diagnose it. The first is its pigmentation: a blotchy, mottled, irregular pattern over a base of pale blue-grey, olive and tan, frequently broken by orange or rust flecking — the source of the aquarium-trade name 'calico damba' — and conspicuously lacking the bold vertical flank bars of its showier congeners. The second is the snout: a fleshy, slightly projecting snout that extends forward of the lips and folds down to cover part of the upper lip, and which in life can flush reddish (hence the FishBase label 'red-nosed Madagascar cichlid'). Sparks distinguishes kieneri from its near-identical sister Paretroplus gymnopreopercularis by its largely scaled preopercle (bare in the sister), a pointed, gently convex forehead (blunt and strongly convex in the sister), and the second lacrimal bone touching the eye margin. Sexual dimorphism is slight and not crisply documented; ripe females become noticeably rounder and deeper-bellied, and the sexes are otherwise told apart mainly by venting and breeding behaviour rather than fixed colour or finnage differences.
Habitat
The kotsovato is endemic to the freshwaters of northwestern Madagascar, and historically had the broadest range of any damba — it is recorded from Lake Kinkony (its type locality, where it lives alongside Paretroplus petiti), from smaller lakes in the Betsiboka drainage, and from rivers including the Kamoro (Kalamilotra) and Mangarahara, spanning roughly 13°S to 20°S. A well-documented second population occupies Lake Ampijoroa, within the Ankarafantsika forest reserve, where it is sympatric with Paretroplus maculatus; collectors there have found both species in water less than two metres deep over a sandy bottom, consistently associated with submerged woody debris rather than open sand or bare rock. It occupies both lentic and lotic water: shallow lakes and the lower-to-middle reaches of slow rivers, typically over substrates of pebble, sand and mud rather than open rock. These are warm, well-mineralized tropical waters; FishBase gives a temperature range of about 75–82 °F, and habitat and aquarium data place the chemistry on the hard, alkaline side — neutral to distinctly basic, with reported pH spanning roughly 6.5 to 8.5 and moderate to high hardness, the legacy of catchments draining calcareous and volcanic terrain. As a demersal fish of shallow floodplain and lake-margin habitats it lives in the upper few metres of the water column; the Lake Ampijoroa records give a firm upper bound of about 7 ft for that population, and the shallow littoral zone generally is the working figure for the species. Crucially, the kotsovato is the most catholic of the dambas in its tolerances — a breadth of habitat that has let it persist where narrowly specialized relatives have collapsed, and its native lakes are themselves under severe pressure from introduced tilapia, which have displaced native cichlids from most of the region's other lakes and now vastly outnumber Paretroplus even in seine-net samples from the reserves where kieneri still holds on.
Feeding
Paretroplus is a genus of substrate-foraging carnivores, and the kotsovato is no exception: in the wild it works pebble, sand and mud bottoms, sifting and picking for benthic invertebrates. FishBase estimates a trophic level near 2.8, consistent with a diet dominated by small bottom animals rather than fish or plants. The genus is well known for durophagy — several Paretroplus carry robust, molarized pharyngeal teeth in the throat that crush hard-shelled prey, and aquarists keeping the larger species report that they relish snails and shell-on shrimp. The kotsovato, smaller and shallower-bodied, sits at the lighter end of that spectrum; its precise wild diet has not been quantified, but it is best understood as a benthic invertivore that takes aquatic snails and other molluscs along with insect larvae, crustaceans and worms turned up from the substrate. Its foraging technique is distinctive within the genus: rather than mouthing or gulping substrate outright, P. kieneri sifts by sweeping its head from side to side over the bottom, working small pits into the sand or mud as it searches — a method it shares with P. maculatus and P. menarambo but not with the genus's more rock-oriented species. In its native lakes and rivers it functions as a mid-level benthic predator of the soft-bottom and pebble zones, a role shared with — and now largely usurped by — the introduced tilapia and snakeheads that have spread across western Madagascar.
Mating
Unlike the mouthbrooding cichlids of the African Rift lakes, every Paretroplus is a biparental substrate spawner, and the kotsovato forms monogamous pairs that share the work of reproduction. Outside breeding it is a comparatively mild, even sociable fish — the least aggressive of the dambas — but a pair preparing to spawn becomes territorial and will defend a chosen site against tankmates and conspecifics alike. Pair formation in this genus follows the familiar cichlid pattern of mutual display, lateral posturing and jaw-locking tests of strength, after which a settled pair selects and cleans a spawning surface. In Madagascar local fishermen report that the damba breeding season falls in the latter half of the rainy season, when warming, rising water presumably triggers reproduction, though this has not been formally confirmed. The kotsovato's relatively even temperament and willingness to pair make it far easier to bring into breeding condition than the boisterous Paretroplus menarambo or the larger Paretroplus damii — a large part of why it was the first of the genus to spawn in captivity.
Breeding
The kotsovato is a substrate spawner, and unlike some of its more cave-dwelling relatives it shows a clear preference for open, horizontal surfaces rather than crevices or overhangs — aquaculture-pond observations describe P. kieneri spawning on cleared, flat ground in the open rather than seeking out a cave. The eggs themselves are large for the fish's size, about 0.5 in across and a yellowish-tan colour reminiscent of many mbuna eggs, and — in a detail that separates the genus from the related Paratilapia, whose eggs form loose, grape-like clusters — each egg is attached individually to the substrate rather than to its neighbours. Both parents guard and fan the clutch, with the female typically staying closer to the eggs than the male, and the eggs hatch in about three days into fry that are roughly twice the size of newly hatched Paratilapia polleni fry. Once free-swimming, the young are actively herded rather than simply guarded: the parents lead them into deeper water and forage alongside them, stirring up silty substrate so the fry can feed from the resulting cloud of disturbed material. A brooding pair takes on a distinctive appearance during this period — both parents darken to a blackish hue and develop a pale white patch on the snout, a signal that appears to warn off other conspecifics from approaching the brood. In pond culture, parental care has been recorded lasting up to three months post-spawning, considerably longer than the comparable period in Paratilapia polleni, and once care ends the siblings of a brood continue to school together rather than dispersing immediately. Pair bonds in aquaculture settings have been observed to persist across multiple spawns rather than dissolving after a single brood. In aquarium conditions pairs have also used rocks, flowerpots, ceramic tubes and artificial caves as alternative spawning surfaces, so the open-substrate preference documented in ponds is not an absolute requirement in captivity. Published clutch-count figures specific to kieneri are scarce; congeneric dambas lay on the order of a few hundred eggs per spawn, which is the genus-typical expectation here. The kotsovato holds a place in aquarium history as the first Paretroplus ever bred in captivity, with successful spawnings achieved in France, in outdoor ponds in Florida, and in tanks at the Bolton Museum Aquarium in the UK. One persistent obstacle across the genus is the parents' tendency to eat their own eggs in the confines of a tank, so breeders working with these rare fish often pull and artificially hatch the eggs to secure a brood — a precaution that matters more for the conservation-priority dambas than for the relatively prolific kotsovato.
In the aquarium
Among the Madagascan cichlids the kotsovato is the kindest to the keeper: small by damba standards, tolerant of a wide range of water, comparatively peaceful, and the easiest of the genus to breed. It is, however, genuinely rare in the trade — almost never a shop fish, and circulated mostly through specialist clubs and a handful of breeders in North America, Europe and Southeast Asia working with captive-bred or wild-derived stock. A pair or small group needs a tank of at least about 105 US gal; a long footprint matters more than height, since these are bottom-oriented fish. Décor should follow the biotope — a substrate of sand and smooth pebble that the fish can sift, scattered driftwood and rockwork, and at least one cave, flowerpot or ceramic tube to serve as a spawning site and a retreat. Water should be warm and on the hard, alkaline side: 75–86 °F (the upper part of that band suits them; many keepers run the Malagasy cichlids around 82 °F), pH roughly 7.0–8.5, with moderate to high hardness. These fish need warmth more than typical community tropicals do, and chronic low temperatures stress them. Filtration should be generous and the tank well maintained — these are robust fish but not waste-tolerant. Feeding is straightforward: they take quality sinking pellets and flake readily and should be offered varied frozen and live foods, with shell-on items such as snails and small shrimp a worthwhile nod to the genus's durophagous habits. On compatibility, the kotsovato is slightly aggressive at most and only territorial when breeding, so it mixes well with similarly sized, even-tempered tankmates — the gentle Ptychochromis grandidieri is a natural companion. It can also be housed alongside Paretroplus petiti or Paretroplus dami without hybridization becoming a practical concern, though very occasional hybridization between Paretroplus species has been reported and should not be treated as impossible. The one combination to avoid on genetic grounds is P. maculatus or P. menarambo, which are close enough relatives of P. kieneri that housing them together carries a real hybridization risk; boisterous P. menarambo is in any case best kept apart unless the tank is very large. A more basic rule governs how the group itself is assembled: Paretroplus, kieneri included, should be kept in groups of six or more raised up together rather than introduced as adult strangers, since putting two unfamiliar adults straight into the same tank will very likely end with one of them dead. Avoid pairing two territorial species in cramped quarters, and keep an eye on a spawning pair, which will clear a defended patch around its nest. Difficulty is best described as intermediate: the husbandry is undemanding, but the fish's rarity, slow growth and the responsibility of keeping an endangered species place it beyond the casual beginner.
Conservation
The IUCN Red List assesses Paretroplus kieneri as Vulnerable (VU), under criteria B1ab(i,ii,iii,iv), assessed on 2 July 2016 by T. Ravelomanana and J.S. Sparks, with the population trend listed as unknown. That makes the kotsovato one of the less imperilled dambas — several of its congeners are Critically Endangered or feared extinct in the wild — but 'less imperilled' is a relative judgement on an island where the entire endemic freshwater fauna is in steep decline. The pressures are the same across the genus: catastrophic deforestation and the erosion and siltation that follow it, the draining and degradation of the shallow lakes and floodplains the dambas depend on, and above all the introduction of tilapia and snakeheads as food fish, which have come to dominate catches that once supported substantial native damba fisheries. Where local fishermen formerly relied on Paretroplus, the kotsovato now makes up a vanishing fraction of the catch, if any at all. Its broad former range and wide tolerances have so far cushioned it, and a thread of captive breeding — in France, Florida, the UK and among hobbyists in North America and Asia — provides a measure of insurance. But the trajectory of Madagascar's freshwater habitats means even this relatively resilient damba cannot be treated as secure.