News
SpeciesScientists Discover Mysterious New Fish in the Red Sea – and Have Never Seen It AgainOceanEye to eye with Britain's hidden sharks at SharkAdemy - OceanographicRiversIn October, biologists surveying a New York harbor for invasive fish pulled up a bright yellow one. It wasn't an invasive species at allOceanShedd Aquarium Sends Shark Eggs to Bolster Wild PopulationsSpeciesA rare fish has been found in Lake Ontario, North America, whose entire body is golden. It is a nati..OceanThe Great Sea Reef Is Fiji’s Wildest Dive, and a New Frontier for ConservationOceanEckerd College professor contributes to designating Biscayne Bay an Important Shark and Ray AreaSpeciesRio Verde Grande Survey Identifies Fifty-Three Fish Species Facing Flow ReductionsFisheriesAdams River Salmon Run in Thompson-NicolaIndiaHilsa production dropped 26% in five years, fisheries minister tells parliamentSpeciesScientists Discover Mysterious New Fish in the Red Sea – and Have Never Seen It AgainOceanEye to eye with Britain's hidden sharks at SharkAdemy - OceanographicRiversIn October, biologists surveying a New York harbor for invasive fish pulled up a bright yellow one. It wasn't an invasive species at allOceanShedd Aquarium Sends Shark Eggs to Bolster Wild PopulationsSpeciesA rare fish has been found in Lake Ontario, North America, whose entire body is golden. It is a nati..OceanThe Great Sea Reef Is Fiji’s Wildest Dive, and a New Frontier for ConservationOceanEckerd College professor contributes to designating Biscayne Bay an Important Shark and Ray AreaSpeciesRio Verde Grande Survey Identifies Fifty-Three Fish Species Facing Flow ReductionsFisheriesAdams River Salmon Run in Thompson-NicolaIndiaHilsa production dropped 26% in five years, fisheries minister tells parliament
EveryFish
Fresh Pla thu before having their collarbones smashed and their heads bent

Short mackerel

A small silver mackerel vital to Southeast Asian fisheries and cuisine.

Photo: Xufanc, CC BY-SA 3.0, via Wikimedia Commons

The short mackerel is a pelagic fish found in shallow waters across Southeast Asia and Melanesia. It supports major commercial fisheries and holds deep cultural significance in Thailand, where it is known as pla thu.

Share on WhatsApp

  • Max length 34.5 cm, commonly 20 cm
  • Known as pla thu, the fish of the nation in Thailand
  • Catch fell from 147,853 tonnes in 2011 to 20,461 in 2018
  • Traditionally preserved by bending head and boiling in salt water
  • Feeds on zooplankton in warm estuarine and coastal waters

What it is

This species belongs to the mackerel family and displays the typical streamlined shape of its kin. It has a silver body and a somewhat pointed snout. Adults usually reach about 20 cm in length, though they can grow up to 34.5 cm. Sexual maturity occurs at approximately 17 cm. The fish is medium-sized and adapted for life in open water near coasts.

Where it lives

Its distribution covers the shallow marine environments of Southeast Asia and Melanesia. While primarily pelagic, it frequently enters estuarine habitats to feed. The species thrives in surface waters with temperatures between 20 and 30 degrees Celsius. This preference for warm, coastal zones makes it accessible to local fisheries throughout the region.

How it lives

The short mackerel feeds mainly on small zooplankton. It is a plankton feeder that operates in the upper water column. Although it lives in open sea areas, it shows a preference for estuarine conditions. The fish migrates within the Gulf of Thailand, moving from southern waters to northern spawning grounds during specific seasons.

Breeding and life cycle

Spawning activity extends from March through September. Populations release eggs in batches rather than all at once. This prolonged season allows for multiple reproductive events. The migration to northern grounds in the Gulf of Thailand is driven by the need to find suitable areas for this batch spawning process.

Short mackerel
A drawing made by EveryFish from what this page says. It is a diagram, not a picture of the real fish.

Fish and people

Known as pla thu in Thailand, it is considered the fish of the nation. Traditional preservation involves bending the head to the belly and boiling it in salted water. This method allowed transport to inland regions before refrigeration. It is central to Thai dishes like kaeng tai pla and tom yam. The catch has declined sharply, leading to imports from Sri Lanka and Indonesia. It is also commercially vital in the Philippines, Malaysia, and Cambodia.

Status and threats

Fisheries authorities have warned of potential extinction in the Gulf of Thailand. Catches dropped from nearly 148,000 tonnes in 2011 to roughly 20,000 tonnes in 2018. An annual fishing ban aims to protect breeding stocks, but illegal catching of adult females persists. This overfishing threatens the sustainability of local populations.

Fisheries recorded capture of Rastrelliger brachysoma from 1950 to 2009. Data source FAO fisheries
Fisheries recorded capture of Rastrelliger brachysoma from 1950 to 2009. Data source FAO fisheries. Photo: Epipelagic, CC BY-SA 3.0, via Wikimedia Commons
Pla thu (Thai: ปลาทู): steamed and salted short mackerel ( rastrelliger brachysoma ) sold at Thanin market in Chiang Mai, Thailand. This fish is most often eaten fried as one of the dishes together with nam phrik kapi ,
Pla thu (Thai: ปลาทู): steamed and salted short mackerel ( rastrelliger brachysoma ) sold at Thanin market in Chiang Mai. Photo: Takeaway, CC BY-SA 3.0, via Wikimedia Commons
Pla thu, Rastrelliger brachysoma , ready to eat
Pla thu, Rastrelliger brachysoma , ready to eat. Photo: Xufanc, CC BY-SA 3.0, via Wikimedia Commons
Fried short-bodied mackerel [1] (hasa-hasa)
Fried short-bodied mackerel [1] (hasa-hasa). Photo: Ramon FVelasquez, CC BY-SA 3.0, via Wikimedia Commons

Questions people ask about Short mackerel

What is the maximum size of a short mackerel?

The short mackerel can attain a maximum length of 34.5 cm. However, lengths of around 20 cm are more common in catches. The fish reaches sexual maturity at a length of about 17 cm.

Why is pla thu important in Thai culture?

It is called the fish of the nation due to its ubiquity. Historically, it was food for the poor but gained status when King Rama V enjoyed it. It is essential in many dishes and features in local emblems.

How is traditional pla thu preserved?

The gills are removed and the backbone is broken to bend the head to the belly. Three fish fit into a bamboo basket. They are boiled in salted seawater, which allows long storage without refrigeration.

What is the current status of short mackerel fisheries?

Catches have dropped significantly, raising extinction warnings in the Gulf of Thailand. Despite annual fishing bans during breeding season, illegal fishing of adult females continues to reduce stock numbers.

Good reading and sources

Where this page comes from

The facts on this page come from the Wikipedia article "Short mackerel", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.

It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.

Like Short mackerel

All tunas and mackerels
🇨🇱 Chile and 3 moreChilean jack mackerel A pelagic fish vital to global fisheries and salmon feed.Tuna · Coasts and shelves · 1920 🇯🇵 Japan and 1 moreJapanese jack mackerel A silver coastal fish prized in East Asian cuisine.Tuna · Coasts and shelves WorldKawakawa A small, striped tuna of the Indo-Pacific reefs and coasts.Tuna · Coasts and shelves WorldChub mackerel A widely distributed pelagic fish in the Scombridae family, known for its schooling habits and commercial value.Tuna · Coasts and shelves

More from Scombridae

All of them
South AsiaStreaked Spanish mackerel A striped mackerel of the Indian Ocean coastsTuna · Coasts and shelves · 1829 WorldLittle tunny A fast, coastal tuna of the Atlantic and Mediterranean.Tuna · Coasts and shelves · 1810 🇳🇴 Norway and 2 moreAtlantic mackerel Fast-swimming, oily fish of the North AtlanticTuna · Coasts and shelves · 1758 WorldAtlantic bluefin tuna Large, warm-blooded tuna of the Atlantic and Mediterranean.Tuna · Open ocean · 1758

Photo credits on this page

The small pictures above come from Wikimedia Commons under free licences. Some are cropped to fit.

The weekly digest

Every Monday: the fish of the day, new pages on EveryFish, and the conferences and anniversaries of the week ahead.