Taxonomy & naming
Aurich described Paratherina striata in 1935, and it anchors the genus Paratherina — one of three endemic sailfin-silverside genera of the Malili Lakes of central Sulawesi, Indonesia. It belongs to the family Telmatherinidae, the freshwater sailfin silversides, within the order Atheriniformes — the same assemblage that holds the marine silversides and, more distantly, the rainbowfishes. Eschmeyer's Catalog of Fishes governs the valid name: Paratherina striata Aurich, 1935.
The genus name pairs the Greek para, 'beside' or 'near', with Atherina, the classical Greek name for the smelt or silverside — a fish close to the silversides. The epithet striata is Latin for 'striped', after the body markings. Molecular work on the Malili flock (Herder and colleagues, plus the microsatellite study of Walter et al.) treats Paratherina as a small monophyletic radiation alongside the other endemic genera Telmatherina and Tominanga, all of them diversified within this one isolated lake system.
Morphology
This is a slender, laterally compressed silverside reaching about 5.5 in total length. Length at first maturity is estimated at around 5.5–6 in, which makes it a comparatively large-bodied member of the Malili sailfin-silverside flock. The body is elongate and built for sustained swimming in open water, in keeping with its pelagic habit.
Like the rest of its family, it carries the divided dorsal fin of the sailfin silversides and the silvery, translucent colour of open-water atheriniforms; the epithet striata points to fine stripes along the flanks. Life-colour and fin-ray data are sparse in the general literature, and the showy sexually selected fin and colour ornaments documented in the related Telmatherina are not well characterised for Paratherina — so anything beyond the basic body form is better left unstated than guessed.
Habitat
The species is endemic to the Malili lake system of central Sulawesi, Indonesia — Lakes Towuti and Mahalona, with historical records from the small connected hill-lake Lontoa (also written Wawontoa or Wawantoa). These are ancient tectonic lakes lying around 2–3 degrees south of the equator, fed and linked by rivers including the Tominanga, which runs from the older Lake Mahalona to the younger Lake Towuti and keeps the two populations in genetic contact.
A freshwater, non-migratory fish, it holds to the off-shore and in-shore open waters rather than dense vegetation or rocky margins. The Malili lakes are clear, deep, and chemically distinctive, set in an ultramafic (nickel-rich) catchment, and they have long drawn researchers as a natural laboratory for adaptive radiation. Diversification of Paratherina is thought to have begun in older Lake Mahalona, from which Towuti was later colonised. The Lontoa/Wawontoa population sits in a heavily degraded hill-lake, and recent surveys could not confirm the fish there at all.
Feeding
It feeds in the open water, mid- to upper-column. FishBase places it at an estimated trophic level of about 3.2 — a diet of small animal prey rather than plant material, in practice the zooplankton and small invertebrates of a large lake's pelagic zone, likely topped up with insects and other drifting items.
No gut-content or feeding-ecology study exists for the species, so the picture here is inferred from its pelagic habit, body form, and trophic-level estimate rather than from direct records. It is harmless to humans and of low fishing vulnerability. With no commercial trade and almost no husbandry literature behind it, what can be said with confidence is narrow: this is a small-prey carnivore of the open water, not a grazer or substrate-sifter.
Mating
The Malili sailfin silversides are known to evolutionary biologists for sexual selection and assortative mating, both of which helped drive their rapid diversification; the genus Telmatherina has been a model for mate choice and colour-based speciation within Lake Matano. For Paratherina striata itself, the courtship, display repertoire, and any breeding seasonality go undescribed in the literature, and they are not invented here.
What is documented is the population structure behind reproduction. Microsatellite work shows the Mahalona and Towuti populations still connected through the Tominanga River, so gene flow continues between the lakes rather than the two standing fully isolated. That connectivity is part of why the genus reads as a single small radiation rather than a set of independently evolving units, and it bears on how reproductive isolation does — or does not — build up across the system.
Breeding
The Malili sailfin silversides are egg-layers, and several related telmatherinids attach adhesive eggs to substrate or vegetation — but the spawning mode, clutch size, egg characteristics, and developmental timing of Paratherina striata are not on record.
With the species essentially absent from the aquarium trade, there are no hobbyist breeding reports to lean on, and the scientific literature on the genus has gone to phylogenetics, population genetics, and conservation rather than captive reproduction. Rather than borrow a protocol from better-studied relatives, this profile says only what holds: it is an oviparous open-water fish of an ancient lake flock. The rest awaits dedicated study that, as far as the available work shows, no one has yet published for it.
In the aquarium
This is not an established aquarium fish. A restricted-range endemic of a remote Indonesian lake system, it is rarely if ever exported for the hobby, and no husbandry tradition or captive breeding record exists for it. So this profile prescribes no tank parameters or care routines that cannot be sourced — that would only be guessing.
The rest is context. As a pelagic, schooling silverside from a large clear tropical lake, it would in principle want a long tank with open swimming space, clean well-oxygenated water, and small live or frozen foods, much as other active midwater atheriniforms do. Those are family-level expectations, not tested requirements for this species — and given its Near Threatened status and its scientific weight, P. striata is far better treated as a fish to study and conserve in the wild than as a candidate for the home tank.
Conservation
The IUCN Red List assesses Paratherina striata as Near Threatened (NT) under criteria B1b(iii,v)+2b(iii,v), in an assessment last carried out on 24 June 2018; the population trend is recorded as decreasing. The listing turns on the species' very small range — a restricted-range endemic confined to the Malili lake system — together with a continuing decline in habitat quality and in the number of locations where it persists.
The main pressures on the Malili Lakes are habitat degradation and biological invasion. The catchment is ultramafic and rich in nickel, and regional mining adds sedimentation and water-quality decline; introduced fishes bring predation and competition that endemic silversides are poorly equipped to withstand. The apparent loss of the fish from the degraded hill-lake Lontoa/Wawontoa, where recent surveys could not confirm it, shows how fast a local population can wink out. P. striata belongs to a globally significant endemic radiation shared with Telmatherina and Tominanga, so its fate is bound to that of the Malili Lakes as a whole — and the conservation-genetics literature has flagged the genus by name as a threatened lineage worth protecting.