#teleosts

Parrotfish come in all shapes, sizes and colours and can be found within tropical waters, most prominently in the Indo-Pacific. Their favourite places to live are coral reefs, rocky coastlines and seagrass forests.

Quoy's parrotfish (Scarus quoyi) - François Libert

Why do I like them so much? Well, they take part in a key role within ecosystems, called bioerosion.

Have you ever been to a white, sandy beach before? That is the work of parrotfish! They are predominantly herbivores, scraping algae off of rocks and coral, with some also being able to slice through tough macroalgae (seaweeds). My personal favourites are the corallivores - parrotfish that exclusively feed on coral.

Because of their sophisticated diets, parrotfish have evolved very fancy dentition, where their teeth have rearranged over time to become beak-like (hence their name!) along with evolving strong jaw muscles and a mill-like structure (called a pharyngeal mill), which helps them grind up their food.

Tricolour parrotfish (Scarus tricolor) - François Libert

Since they scrape along coral and other rocky substances all day, they tend to ingest a lot of minerals, including calcium, which is eventually excreted. Long story short, those white sandy beaches are actually the hard work of bioerosion carried out by hundreds of thousands of parrotfish over millions of years.

Just one humphead parrotfish can produce 90kg of sand per day!

School of blue parrotfish (Scarus coeruleus) - Gérard Cachon

Without parrotfish, we wouldn't have those beautiful beaches. But more importantly, they are absoloutely key to the health and structure of tropical reefs.

Tricolour parrotfish (Scarus tricolor) - François Libert

Tonsil like Us

Organ of the immune system akin to our tonsils discovered in the popular model organism zebrafish and other bony fish

Read the published research paper here

Image from work by Julien Rességuier and colleagues

Section for Physiology and Cell Biology, Departments of Biosciences and Immunology, University of Oslo, Oslo, Norway

Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)

Published in and on the cover of Science Advances, November 2023

For the majority of the animal kingdom, the sex of their young is random. However, many species can actually influence their offspring’s sex by altering the temperature at which their eggs incubate! This phenomenon is called temperature-dependent sex determination, and has been observed in most reptiles and some species of fish. The most common example of this is turtles, which choose where to build their nests based on the amount of sun or shade. Cooler incubation temperatures, generally below 27.7°C produce males, while warmer temperatures produce females.

Snubnose Pompano (Trachinotus blochii) Changi, 8th January 2017

Many of the offshore fish farms in the Straits of Johor raise Snubnose Pompano for human consumption, so this carcass could have come from one of the farmed fishes, instead of being of wild origin.

A Guide to Common Marine Fishes of Singapore

Fishing the Philippines

Field Guide to Lombok Island

Fishes of Australia

Australian Museum

The Living Marine Resources of the Western Central Pacific Volume 4

FAO Cultured Aquatic Species Fact Sheets

FishBase

Five new myxosporean species Ceratomyxa cantopona sp. m. and Henneguya calcarifera sp.n. (Myxobolidae) from the gallbladder and the kidney of Lates calcarifer (Centropomidae) and Myxobolus ariae sp.n (Myxobolidae), Myxobolus centropomius sp. n. (Myxobolidae) and Sphaeromyxa bengalensis sp. n. (Sphaeromyxidae) from the gallbladder of marine teleosts Lates calcarifer (Centropomidae), Lutjanus bengalensis (Lutjanidae) and Arius arius (Arridae) respectively off the Bay of Bengal coast of West Bengal, India have been described. Comparative table for each species has been computed with related species to establish their distinctiveness. The myxosporean Henneguya latesi Paperna 1973 has been found pre-occupied by Henneguya latesi Tripathi 1951. Therefore a new name Henneguya papernae nov.nom. has been proposed for Henneguya latesi Paperna 1973.

Spanish Mackerel (Scomberomorus sp.) (?) Tanah Merah, 10th April 2016

A bag of fish parts was found on the beach. Further inspection revealed that the contents comprised various parts of Spanish Mackerel. Whether these pieces of fish were purchased at the market, or came from a fish caught in Singapore waters is unknown. It's also not known why these were dumped on the shore, although there is a possibility that these were intended as bait for some other marine creature.

Scombrids of the world

Morphology, systematics, and biology of the Spanish Mackerels (Scomberomorus, Scombridae)

ieatishootipost: Singapore Fish Files: Spanish Mackerel, Spotted King Mackerel and Korean Seerfish

Four species of Spanish Mackerel have been documented in the waters around Singapore and Malaysia, and these remains may represent any of these species:

Indo-Pacific King Mackerel (Scomberomorus guttatus)

Handlinefishing.com

Fish Species of Singapore

FishBase

FAO Fisheries and Aquaculture Department Species Fact Sheets

IUCN Red List

The Living Marine Resources of the Western Central Pacific Volume 6

Western Indian Ocean Fishing Area 51

Narrow-barred Spanish Mackerel (Scomberomorus commerson)

Handlinefishing.com

Fishes of Andaman Sea

Fishes of Bitung

FishBase

FAO Fisheries and Aquaculture Department Species Fact Sheets

IUCN Red List

The Living Marine Resources of the Western Central Pacific Volume 6

Western Indian Ocean Fishing Area 51

Korean Seerfish (Scomberomorus koreanus)

FishBase

IUCN Red List

The Living Marine Resources of the Western Central Pacific Volume 6

Western Indian Ocean Fishing Area 51

Streaked Spanish Mackerel (Scomberomorus lineolatus)

FishBase

IUCN Red List

The Living Marine Resources of the Western Central Pacific Volume 6

Western Indian Ocean Fishing Area 51

Another possible candidate is the Double-lined Mackerel (Grammatorcynus bilineatus):

Fishes of Andaman Sea

Fishes of Bitung

FishBase

Fishes of Australia

IUCN Red List

The Living Marine Resources of the Western Central Pacific Volume 6

The hundreds of dead fish were reportedly left behind by fishermen at the south end of Patong. Photo: Regional Environment Office 15

Thailand: Mass of dead fish on Patong Beach 'no cause for alarm', say officials By , 2016;

Hundreds of dead fish found washed ashore Patong Beach yesterday is no cause for alarm say local officials, and not the result of toxic shock brought on by wastewater pumped into the bay.

The alarm was raised after people reported hundreds of small fish – all dead – along a one-kilometre stretch at the southern end of of Patong Beach at about 5pm to 6pm yesterday (Dec 19).

"The dead fish came from the fishermen who operate out of Klong Pakbang at the southern end of Patong," Patong Mayor Chalermluck Kebsup told The Phuket News today (Dec 20).

"The fishing community there use beach seines at the south end of Patong Beach. I checked with them and they explained that the small fish were discarded after the fishermen discovered they had caught bigger fish in the nets," she explained."

"I will remind them that their actions affect people's impressions of Patong, and that although they have legal permits to use nets to fish there, they must be responsible and take care of our environment," Mayor Chalermluck noted.

"This was not the result of wastewater. If it were, I must see the initial report about it so I can fix problem the quickly."

Mayor Chalermluck pointed out that her office is keeping an eye on pollutants flowing from the canal into Patong Bay.

"I can show last month's water test results to The Phuket News tomorrow (Dec 21),"” she said.

Pornsri Suthanaruk, Chief of the "Regional Environment Office 15", based in Phuket, confirmed that her office had investigated the report, and would not take any further action.

"My officers explained to me that this incident resulted from fishing practices used at Patong Beach, not from polluted water," she told The Phuket News today.

Ms Pornsri noted that her office has long been aware of beach seines used at Patong.

"In this case, it is not necessary yet to conduct water-quality tests, which are costly, and Patong Municipality's wastewater-treatment plant is good enough," she said.

Thousand of dead Tilapia were found at a river near Taman Rumpun Bahagia in Bachang.

Bukit Katil MCA Youth chief Lee Chong Guan and Bukit Katil Gerakan secretary Nelson Goh Jin point at the fish carcasses.

Malaysia: Thousands of dead Tilapia end up in Malacca River By Kelly Koh, 21st November 2016;

The sudden appearance of thousands of dead Tilapia (Oreochromis sp.) floating on the surface of the Malacca River near Taman Rumpun Bahagia in Bachang has left even the state Environment Department puzzled.

Malacca Environment Department director Shafe'ee Yasin however, confirmed that the river was not threatened by industrial pollutants.

"Initial investigations by DOE revealed that the river was not contaminated by industrial effluents as there were no factories nearby," he said.

"We have collected samples of the river water, but we have yet to finalise its results," he said when contacted by New Straits Times here today.

Shafe'ee said based on previous incidents of dead fish found in the Malacca River, the freshwater Tilapia can be assumed to have been killed by a sudden influx of seawater to the opening of the barrage.

"Freshwater fish living in the Malacca River may likely die as they are unable to tolerate the high salinity in the water after mixing with sea water.

"Another possibility is the effects of sediments on the fishes, where they die from low oxygen," he added.

Shafe'ee said the department will not hesitate to take action against industrial operations found to be releasing industrial waste into the Malacca River.

"We will check and take action if industrial sites are found to be releasing effluents including during odd hours," he added.

Checks by the New Straits Times found that the river had since been cleared of fish carcasses.

Meanwhile, Bukit Katil MCA Youth chief Lee Chong Guan and Bukit Katil Gerakan secretary Nelson Goh Jin Juan, who visited the site, urged authorities to identify to cause of the high number of dead fish.