Pseudopercis semifasciata
A 70cm bottom-dweller found off Puerto Madryn, Argentina, in cool 10-18C water, uncommon but a real find for patient divers.
A long, torpedo-shaped fish reaching around 70cm, usually seen resting flat on sand or gravel rather than swimming in open water. Look for a mottled brown-to-grey body with faint darker banding along the flanks and a slightly flattened head with an elongated snout typical of sandperches. It tends to sit still and blend into the substrate, so divers often spot it by the outline first, not the colour.
Divers typically find it lying motionless on sand, gravel, or mixed bottom rather than cruising the water column, relying on stillness and its mottled pattern to go unnoticed. It doesn't spook easily at a slow, respectful approach, giving you time for a good look, though it will move off if crowded. Most sightings are on the seafloor rather than up in the water, so keep your eyes down when working sandy patches near reef structure.
As a member of the sandperch family, it's an ambush predator built for sitting still on the bottom rather than chasing prey through open water, a strategy that also makes it one of the trickier fish to spot despite its size.
Sightings show no detected seasonal pattern, and with an observed range of 10.4 to 18.3C, it seems to tolerate a fair temperature swing across Patagonian seasons, so treat it as a year-round possibility in Puerto Madryn.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Every logged sighting in the data comes from Argentina, with Puerto Madryn standing out as the reliable region for this species. If you're diving Patagonian waters around Puerto Madryn, this is one of the resident bottom species worth scanning the sand for.
Mapping where Argentinian Sandperch is logged…
The strongest and most consistent sightings come from Puerto Madryn, Argentina, where it's logged across numerous dive sites, though always as an uncommon find rather than a guaranteed one.
There's no clear seasonal pattern in the sighting data, and it's recorded across a wide temperature range from 10.4 to 18.3C, so it's best treated as a year-round possibility in Patagonian waters.
Look for a long, cylindrical fish up to 70cm lying still on sand or gravel, with a mottled brown-grey body and faint banding. Its resting posture on the bottom, rather than active swimming, is often the giveaway.
They reach around 70cm in length, making them one of the larger bottom-dwelling fish a diver might encounter on sandy patches near Puerto Madryn.
No, they're not considered dangerous to divers. They're bottom-resting fish that tend to hold still or move away calmly rather than react defensively.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Spotted Sandperch
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