Fish and Marine Invertebrates: General, including behaviour


We've given you two headlines, the first (in blue) being the original, and the second (in red) aims to be a more informative headline, so you can gain an idea of what the article is about more quickly. The source is also given in case you want to track down the original article.

See also:

Book reviews: Fish

Animal Care and Behaviour: Fish


Genetic proof for marine reserves

Marine reserve networks can help increas fish numbers outside reserves

source: New Scientist vol 214 no 2867, June 2nd 2012 p18

Garry Russ and team from the ARC Centre of Excellence for Coral Reef Studies, Queensland, Australia, have found that marine reserve networks can help to increase fish numbers outside reserves. They examined the DNA from stripey snapper and coral trout in and outside reserves in the Great Barrier Reef. The reserves account for 28% of the total area. The juvenile fish of these species had doubled in number outside the reserves. The team plans to examine the catches of local fisheries, to assess the impact of reserves on commercial fishing.



Most fish in the sea evolved on land

Ray-finned fish evolved from fresh water fish

source: Colin Barras
New Scientist vol 213 no 2851, February 11th 2012 p17

Greta Vega and John Viens from Stony Brook University, New York, have discovered that ray-finned fish, which account for 96% of marine and freshwater fish on earth, descended from freshwater fish. Ray-fins only appeared in the sea some 170 million years ago. Most dolphins and whales also evolved in fresh water. Wiens believes that lakes, rivers and land may be less prone to mass extinctions than seas, so may be able to re-seed oceans after the loss of sea species. However, lakes and rivers are now threatened by pollution and dams, which could  affect their ability to resupply oceans, at a time when increasing acidification is threatening ocean life. 


Lungfish doesn't need limbs to walk

African lungfish use pelvic fins for walking

New Scientist vol 212 no 2843, December 17 2011 p16

Heather King from Chicago University, Illinois, has found that African lungfish use their pelvic fins for walking on lake beds. These fins have a similar shape to those used by ancient vertebrates when they initially walked on land. Fins may have been used for walking prior to vertebrates evolving more specialised limbs.



Harrassed fish bait their friends

Female guppies get bad-tempered after sexual harrassment

source: New Scientist vol 212 no 2833, October 8 2011 p16

Female guppies get bad-tempered with other females after sexual harassment. Safi Darden from Exeter University, UK, has discovered that females are more likely to push and chase fellow-females following harassment by a male.


The fish that sounds like a screaming baby

Toadfish makes non-linear sounds for urgent calls

source: New Scientist vol 210 no 2812, May 14 2011 p15

Western Pacific three-spined toadfish can produce non-linear sounds for urgent calls. Other species of fish can produce non-linear sounds, but three-spined toadfish can make more complex sounds using their swimbladders. Their calls have been studied by Aaron Rice from Cornell University, New York.


Evolution in the fast lane

Adaptation of marine sticklebacks shows that evolution can be rapid

source: Michael Le Page
New Scientist vol 210 no 2806 April 2 2011 starts p 32, 5 pages long

Marine sticklebacks can adapt fast to fresh water conditions, and lose armour plate as part of this adaptation. Michael Bell, biologist from Stony Brook University, New York, has studied sticklebacks from Loberg Lake, Alaska. He found, in two decades to 2007, the fish had evolved the trait of light armour. The fish also developed smaller gills. Similar changes have been seen in Norwegian sticklebacks cut off from marine water. Evolution tends to be slow, according to DNA and fossil evidence, but cases of rapid evolution are more common than previously thought. Studies of sticklebacks elsewhere show that genetic diversity fosters adaptation. 

Rapid evolution may be undetected, because new species may disappear before leaving records. Species may divide then merge back, as has happened in Lake Victoria, Africa. Cichlid species in the lake have begun breeding with one another in response to poor visibility from human activity, which prevents the fish from differentiating between species. Selection is a stronger pressure than thought. Organisms evolve rapidly as environments change, but most evolutionary change is cancelled by further change.


How the seahorse gained its shape

Seahorse curves help them grab distant prey

source: New Scientist vol 209 no 2797, January 29 2011 p15

The shape of seahorses allows them to grab prey at a distance, according to Sam van Wassenbergh, a biologist from Antwerp University, Belgium. He and his team created mathematical models comparing seahorses with pipefish, which lack the seahorses' curved shape. The seahorses' curves give their necks stability and elasticity, giving them greater range. This helps to offset their poor swimming abilities.


Super fish salvages dead zone

Gobies can recycle nutrients

source: New Scientist vol 207 no 2770, 24 July 2010  p17

Researchers from Bergen University, Norway, have found that bearded gobies can survive low oxygen levels and recycle nutrients for other fish. The researchers studied waters off Namibia, where jellyfish and algae have infested a fishery. They found that the gobies are bottom dwellers in the day, surfacing at night. The gobies eat dead algae and jellyfish. Hake and horse mackerel eat gobies. This research was first reported in Science, DOI: 10.11261 science.1190708.


California divided over GM pet fish

California may ban sale of GM pet fish

source: Guardian December 3 2003 p17

The GloFish, a genetically modified zebra fish which glows when the lights are turned out, will be offered for sale in the US from January 2004, though sale of the fish may be banned in California. Wildlife officials do not see the fish as a threat, but public interest and environmental groups oppose the sale of the fish, which was developed in Singapore, and bred in Florida.


Scientists discover deep sea enigma

Census of Marine Life finds new species

Source: Suzanne Goldenberg
Guardian October 24 2003 p18

The Census of Marine Life has involved over 300 scientists from 53 nations, and has catalogued 15,304 fish species, while identifying three previously unknown species every week. The census is scheduled to end in 2010. Much of marine life is still unknown to humans, since exploring the deep seas has been expensive, until remote-controlled underwater vehicles, and submersibles were developed. The impact of climate change, pollution and overfishing cannot easily be assessed without a better idea of marine life. The project also involves tracking salmon and tuna fish, to observe their migrations.


In the swim with an eye on the clock

Fish can tell the time

source: Kirsty Scott
Guardian October 1 2003 p13

Plymouth University psychologist, Phil Gee, has trained fish to hit a lever a a specific time to obtain food. The fish also pressed the lever when they were not fed, until the time to feed them had elapsed. Fish appear able to adapt and learn, as well as tell the time. This research could help fish farmers who could train fish to come to a particular spot for feeding at a particular time. Norwegian research has found that fish can be trained to come to a spot in a fjord, in response to a sound. 


Are fish really more intelligent than monkeys?

Research on fish intelligence

source: Alok Jha
Guardian Life supplement September 4 2003 p3

Fish show evidence of social intelligence, according to biologist, Culum Brown, from Edinburgh University, Scotland. He has co-authored a report on fish intelligence, and argues that fish can co-operate to find food or avoid predators, punish and manipulate other fish, and seek reconciliation. Fish are able to identify others from the same shoal, and can navigate mazes, as well as use tools and build nests. They also have long-term memories. One fish remembered where a hole was in a fishing net, akmost a year after the fish had first found the hole, Brown records. He argues that captive fish need changes in their environment, to make their lives more interesting. 


The world according to carp

Pleasures of keeping koi carp

source: Sally Weale
Guardian G2 July 24 2002
starts p4, 2 pages long

Koi carp have become popular in the UK, though they can be expensive to buy and keep. Their food can cost from 60 pounds to 70 pounds sterling for a bag of 10 kilos, and the cost of heating their ponds in winter can be as much as 30 pounds a week. Koi have preferences for some types of music, and can eat food from their owners' fingers.

Koi generally live from between 40 and 50-years-old, with some reaching 100-years-old. Females grow larger than males. There are some 5,000 members of the British Koi Society, which had some 8,000 members at its peak. Koi can cost from 75 pounds sterling, and prices of between 1,000 and 10,000 pounds for one fish are not uncommon.



Commercial fish farms 'wiping out' wild salmon

Threats to salmon from fish farms

Source: Paul Kelbie
Independent June 1 2002 p13

The World Wide Fund for Nature has noted a sharp drop population of wild salmon in Europe and North America. This drop is attributed to fish farming, and conservation groups are seeking greater control of fish farms. Escaped fish from farms can interbreed with wild fish, weakening the gene pool for wild salmon. Wild fish can also become infected by farmed fish, and compete for habitat and food with them. Environmentalists are calling for the North Atlantic Salmon Organization, which represents salmon fishing, to take action. They also want river mouths to be free of fish farms, in order to protect returning salmon.


'Fluorescent fish' give the green light to GM pets

Controversy over genetically modified fish

source: Robin McKie Observer June 15 2003 p2

enetically modified fish that glow with different colours are to be sold in the US, a move that has led to controversy. Night Pearl fish were created at National Taiwan University, by a researcher, Professor H.J. Tsai, who was seeking to create fish with easily visible organs for studying. He used jellyfish genes to produce glowing zebra fish . His research attracted the interest of fish produce firm, Taikong Corporation, which offered help with research funding. The resulting fish have been offered for sale in Taiwan, and are also to be sold in the US. They come in green or red. A glowing dragon fish is the next project for the Taiwanese research team.

Critics fear that natural populations of fish could be polluted by these genetically modified fish, although Professor Tsai argues that over 90% of the zebra fish have been sterlized. they are still concerned about the risks from the remaining fish.

Another research area which has aroused controversy is for tropical fish to have genes inserted so they can survive at colder temperatures. This could lead to the new types of fish being released and surviving in British waters, argues Derek Lambert, who edits 'Today's Fishkeeper'.


Pet eel could face eviction to nearby canal

German family keep pet eel in bath for 34 years

source: Independent January 29 2003 p12

A German family has a pet eel which has spent 34 years living in a bath. The eel is called Aalfred, and was caught in 1969 by Paul Richter, who planned to eat it, but his children protested. The eel has attracted the attention of the German press, and there have been protests from animal rights activists who claim that Aalfred's bathtub environment is unnatural, so he may be sent to live in a canal.


We hear that....

Concern about Northern snakehead fish from China found in Maryland, US

source: New Scientist July 13 2002 p18

There is concern that Northern snakehead fish found wild in China could spread in the US, after one was found close to a pond in Maryland. The fish is a predator which can travel out of water, with the use of its pectoral fins. This fish is a predator, and is a metre long. The one found in Maryland could have escaped from an aquarium, or from a fish market. Maryland officials have asked members of the public to kill any of these fish they might find, because they could cause harm to the ecosystem.


Pirates raid Mozambique sea treasures

Rare fish caught off Mozambique for pet fish market

source: Tim Judah
Observer June 16 2002 p20

Marine life living off the coast of Mozambique is under threat, due to the activities of dealers from South Africa, Tanzania, Portugal and China, who pay local people to catch exotic fish and other species, some to be eaten, others to be used for decoration or to be kept in aquaria. Mozambique is a very poor country, and trade in exotic species can bring wealth, so there has been opposition to environmentalists who want to study the trade, and who are against it. Even some government officials from Mozambique may be involved in the trade. South Africans tend to specialize in fish dealing, while Mozambican and Portuguese dealers buy shells and coral in very large amounts, which threatens the reefs off Mozambique. Dynamite is being used by Tanaznian fishermen to blast reefs of northern Mozambique. Chinese dealers are interested in shark fins, believed in China to be aphrodisiacs and sea cucumbers, which are eaten.

There has been some effort to preserve marine life, however, for example, the Quirimbas national park includes sea areas as well as land, and there are some sea patrols by officials.


Guppy love

Why female guppies like males with orange spots

source: New Scientist March 23 2002 p27

A team from the University of Toronto, Canada, led by Helen Rodd, has carried out research on why female guppies prefer males with orange spots. They used plastic disks of different colours to test the preferences of wild guppies, both females and males. They found that orange was the favourite colour of both sexes. This could be because cabrehash fruit is a favourite food of guppies, and the fruit is orange, Rodd thinks. The evolution of male guppies may have been affected by this preference, she believes.


Dining in the dark

Hunting methods of catfish in dark water

source: Eugenie Samuel
New Scientist June 16 2001 p21

Thomas Breithaupt and Kirsten Pohlmann are two researchers from Konstanz University, Germany, who have investigated how catfish hunt in the dark. They found that catfish that are hunting guppies follow eddies created by guppies’ tails. The guppies make both primary eddies, from the movement of their bodies through water, and secondary eddies, from their tail movements. These secondary eddies provide useful information of the direction the guppy is going. Other predatory fish may use similar methods.

The researchers want to use this information to develop a robot, which could help marine biologists study the movements of fish, through tracking eddies left by passing fish.


On golden pond

History of pond fish keeping

source: Susie Green
Guardian Weekend February 23 2002 p59

Pond fish have been kept as far back as Roman times. Some Roman ponds had bridges and walkways, and places for people to dine by their ponds. Cicero called the Roman ruling class ‘piscinarii’ because of their enthusiasm for fish ponds. They kept different fish from modern pond fish keepers, and their favourites included mullets, and members of the eel family. Some eels were able to recognise their owners and come to be fed. Titbits fed by Crassus, a Roman general, to his eel, included milk curds and green figs. Crassus even put earrings and necklaces on his favourite eel. Lampreys often bite, and they were used by another Roman to attack people thrown into the water.

Koi carp have become more popular in modern times. These fish can distinguish between humans, and recognise their owners, while hiding from 
strangers. Koi are able to suck, since they have no teeth at the front of their mouths. Some koi keepers give their fish a baby’s dummy to suck, with honey on it. Koi also like other titbits, like fruits, cockles and prawns. Koi tend to be lethargic when it is cold, and many koi owners spend large sums heating their ponds.


Scientists name 10 most threatened coral reefs

Concern about destruction of coral reef habitats

source: Steve Connor
Independent February 15 2002 p14

There is concern about the destruction of coral habitats, especially since they house a large proportion of marine life. Around a third of marine wildlife species are found in coral reefs, though they account for only 0.017% of the total ocean environment world wide, according to University of York’s Callum Roberts, speaking at the American Association for the Advancement of Science conference in February 2002. Biodiversity can be affected when only small areas are destroyed. There are ten coral reefs seen as especially diverse and under threat, and they include reefs off the Philippines. Some marine life has already become extinct, such as green wrasse fish.

There has been less effort to conserve marine species than land species, in terms of setting up protected areas, yet such areas could be economically beneficial in providing hatcheries and safe places for younger fish, so that there are enough fish available to catch. This has been found in the Caribbean, where marine reserves off St Lucia were set up, and catches had almost doubled five years afterwards. 


In the ocean, you’re either red - or dead

Red fish are less easily seen in deep water

source: New Scientist February 9 2002 p23

Fish at levels of below 20 metres under the surface of the ocean are less visible to predators when they are red, while fish close to the surface are less visible if they are blue. Researcher, Sonke Jonsen, from North Carolina’s Duke University, has developed a mathematical model to show the passage of light in tropical oceans, and his findings are backed by observations that blue fish do indeed tend to be found closer to the surface, while red fish and other red animals are found in deeper ocean water.


Musical fish

Carp trained to respond to different types of music

source: New Scientist January 19 2002 p24

Three carp have been trained to respond to different types of music, and differentiate between Bach and John Lee Hooker. The research was carried out at the Rowland Institute for Science, Cambridge, Massachusetts, where researcher, Ava Chase, played the fish music, and rewarded them with food to respond to different types of music. The fish were also able to categorise music as either classical music or blues, even when played music they had not heard before, from different composers and musicians. This skill may reflect the needs of wild fish.


Seahorses breed successfully in a Cornish fishtank

Cornish aquatic centre raises large brood of seahorses

source: Michael McCarthy
Independent January 11 2002 p10

Mid-Cornwall Aquatics has succeeded in raising 100 seahorses from a brood of 160 born to a pair of Hippocampus reidi, (tropical seahorses) at the centre. The fry have reached four inches long, compared with the adult size of seven inches, and have reached the age of four-and-a-half months. This is thought to be the biggest brood raised by commercial fish keepers.

Owner of the fish centre, Les Wiley, believes the diet he gives the seahorses is the reason for his success. Their diet includes marine rotifers and small shrimps from estuaries nearby.

There are 32 species of seahorses that have been classified, and Hippocampus reidi are native to western tropical regions of the Atlantic. This species is under threat in the wild, and breeding them commercially may help wild seahorses, by reducing numbers caught in the wild. Wiley plans to sell the brood as adults, charging 50 pounds sterling a pair. Seahorses are generally under threat world wide, especially due to demand for them as ingredients for Chinese medicines. The Philippines is the main area for seashore fishing. Conservationists are seeking to educate local communities to avoid overfishing.

Seahorses are in the same family as sticklebacks. They breed in a peculiar way, with the female putting her eggs in the male, which later gives birth. They also form life-long pairs which carry out swimming dances when the meet each morning. 


Mayflies dying out on legendary trout streams

British river fish suffer from decline in numbers of river flies

source: Michael McCarthy
Independent December 1 2001 p16

English rivers may have become cleaner in terms of having less sewage and industrial waste going into them, but river flies have dropped in number, which affects the fish that feed on them. Mayflies have especially been affected, and trout are fond of mayfly, which is why mayfly imitations are used by anglers. Fly numbers are estimated to have fallen by some two thirds since 1945, with much of this fall occurring since 1980. Intensive agriculture is thought to be the main cause, since there has been an increase in agricultural run-offs, which may include pesticides. Water companies also use river water, leaving less water to absorb pollutants, which become more concentrated.

The Wiltshire Fishery Association and the Environment Agency carried out a survey of southern England, using information from people fishing chalk trout streams, as well as owners of fisheries, and riverkeepers. These streams have traditionally been pure, with large fish and large numbers of flies, and mass mayfly hatchings, especially in late May and early June. The results of the survey indicate sharp drops for many mayfly species, and there is concern about what this implies for the state of English rivers.


Swim for it

Hatchery fish need training to avoid predators

source: James Randerson
New Scientist October 6 2001 p11

Hatchery fish need training to avoid predators. They are often bred to restock rivers and seas, especially in Japan, Norway and the US. Under 5% of salmon released from hatcheries are believed to survive to be adults. University of Edinburgh’s Culum Brown and Cambridge University’s Kevin Laland have studied fish behaviour, and they see training in shoals as a way for fish to survive. Fish tend to learn from each other in shoals, for example, by observing escape reactions. Demonstrator fish could teach naïve shoals by reacting to predators behind screens. University of Helsinki’s Sampsa Vilhunen has taught Arctic charr to avoid predators. The predators were fed on charr, and then put in another tank. Naïve charr put into the water where charr had been eaten learnt that the predator should be avoided.

Hatchery fish tend to be fed until they are quite large in a bid to protect them from predators, since the smaller predators are unable to eat larger fish. Training the fish would save on food and allow for an earlier release of fish from hatcheries. This research was reported in more detail in Journal of Fish Biology vol 59 p471.


Total recall

Rainbow fish have good memories

source: New Scientist October 6 2001 p27

Research on Australian crimson spotted rainbowfish has found that they are able to remember an escape route 11 months after they learnt it. The research was carried out by Edinburgh University’s Culum Brown, who used a trawl net in a tank to simulate a predator. The fish could only escape through the middle, where there was a hole in the net. Their memory of the escape route was almost as good when they were tested 11 months afterwards, and these fish only live for under two years.


How to melt a heart of ice

Fish use natural antifreeze

source: James Randerson
New Scientist August 25 2001 p7

Some types of fish found in the Antarctic and Arctic, such as cod, make their own antifreeze. This antifreeze is comprised of glycoproteins that prevents ice crystals from developing in the fishes’ tissues and blood, so protecting their cells structures and membranes from rupturing. Researchers from the State University of New York believe that they can produce this antifreeze in large amounts, because they have developed a stable version of it, which could have a number of applications such as protecting human tissue from damage at very low temperatures.


Shoal owner

Fish ranching

source Geoff Watts
New Scientist July 28 2001
Starts p40, 4 pages long

Fish ranching is an idea proposed by University of Plymouth researcher, Jonathan Lovell. This is a different technique from fish farming, which may lead to pollution and disease, since the fish have less space. Ranching involves training fish to swim in a certain direction in response to a stimulus, and using food rewards. Lovell has carried out work in tanks using goldfish, carp, bass and mullet. He estimates that it takes two weeks to train fish, feeding them twice a day, and their ability to respond lasts for a minimum of four months.

Other work using conditioning techniques to train fish is being carried out by Jens Balchen in Trondheim, Norway, where researchers at the University of Science and Technology have been carrying out field trials. One use for conditioning is to store fish alive in a closed-off bay, when there are too many fish for a freezing plant to deal with. They can be recaptured later using conditioning.

There are legal issues that need to be tackled, if this technique is to become widespread, such as what to do about rustlers who use sound generators to catch fish fed by someone else.