May 172014

Original story by Paige Taylor, The Australian

ACOUSTIC tags used to track great white sharks off the West Australian coast have been put to use on a menacing population of giant goldfish in the Western Australia’s southwest.
A 2kg Goldfish from the Vasse River, south of Perth.

A 2kg Goldfish from the Vasse River, south of Perth.

The former pets and their offspring, some 40cm in length and weighing 2kg, are among invasive feral fish entering the southwest waterways, where for the first time unique local fish are outnumbered by alien species. Continue reading »

May 152014

By Greg Wallis (pseudechis) at YouTube

The Tarpon or Ox-eye Herring (Megalops cyprinoides) is a common fish found in the rivers and coastal areas of northern Australia. It is also found through much of the tropics from east Africa, across the Indian Ocean to South-east Asia. It is also commonly referred to as the Indo-Pacific Tarpon outside of Australian waters.The Tarpon/Oxeye Herring from Australian waters should not be confused with the much larger Atlantic Tarpon (Megalops atlanticus) from the americas. The fish at the end of the video is a Black Catfish (Neosilurus ater).

Although the Oxeye Herring can grow to well over a metre, it is more commonly seen up to around 50 cm. Larger fish are normally found in marine waters.

The tarpon can often be seen flashing and “gulping” air at the waters surface; it can tolerate low oxygen levels in the water due to it’s ability to supplement it’s oxygen supply via air that is gulped into it’s modified swim bladder.

Tarpon are highly regarded as a sportfish because of their fighting ability on light tackle. They are often observed actively feeding on the surface of tropical billabongs in the early morning and late afternoon where they are easily caught on flies and lures although they are regarded as poor eating because of the large number of fine bones.

For more information on Oxeye Herring see the Fishes of Australia website at:…

CAAB Taxon Code: 37054001

May 102014

By TAMALIN TV at YouTube

Underwater video footage of wild Melanotaenia boesemani.

This clip was made by Martin at Kali Tentara the famous river in Ayamaru Distric and as tributary to Ayamaru Lakes of the Vogelkop Peninsula, West Papua..

Rainbowfish seen underwater of cristal clear water of Ayamaru river one of the tributary river the Ayamaru Lakes.

Boeseman’s Rainbowfish at Korom River, Aitinyo Lakes headwaters, New Guinea

May 102014

Original story by Rebecca Kessler, evironment360

Originating in Europe, “nature-like” fishways are now being constructed on some U.S. rivers where removing dams is not an option. Unlike traditional fish ladders, these passages use a natural approach aimed at significantly increasing once-abundant runs of migratory fish.
A fishway constructed at Seaforth Creek helps with fish spawning runs. Photo: Dragi Markovic

A fishway constructed at Seaforth Creek helps with fish spawning runs. Photo: Dragi Markovic

On a chilly April morning, when the buds had opened just enough to cast a faint red haze on the trees, Jim Turek drove me out to see how his latest construction project was faring after a long winter. In December, work crews completed a project designed to let fish swim over the old Kenyon Mill Dam spanning the Pawcatuck River in Richmond, Rhode Island. The dam, and one that probably preceded it, had been blocking the fish’s path from the sea to their upriver spawning grounds since the 1700s. What was once likely an annual migration of hundreds of thousands of river herring and tens of thousands of American shad had dwindled to just a few hundred fish. Runs of Atlantic salmon had long since disappeared. 

This was not your typical fish ladder — narrow concrete, metal, or wood contraptions that look a bit like flooded pedestrian highway overpasses. Instead, work crews had installed boulders in sweeping arcs or V-shaped formations clear across the river to create a series of broad pools. These ramped gradually from the natural riverbed up the now nearly submerged 5-foot-tall dam, whose top they had replaced. Continue reading »

May 092014

The ConversationOriginal story by Ron Thresher, CSIRO at The Conversation

A genetic modification that creates male-only populations could give us a new weapon against invasive fish such as carp that plague our waterways.
Carp have spread throughout Australia’s waterways - but CSIRO is hoping to bring a new genetic weapon to bear on them. Photo: Kletr/

Carp have spread throughout Australia’s waterways – but CSIRO is hoping to bring a new genetic weapon to bear on them. Photo: Kletr/

“Daughterless technology”, which works by removing females so a population can no longer breed, has previously been used to tackle mosquitoes. But new CSIRO research shows that it also works on fish.

The technology is safe and could be used to greatest effect with other forms of pest control. It might also be used to control other vertebrate pests such as cane toads. Continue reading »

May 072014

Where: Forest Lake Boulevard Park

Date: Sunday 25 May 2014

Time: From 9am – 12pm

Cost: Free

Learn how to identify pest fish species and the impact they pose on our native fish and aquatic habitat. During the event, residents will able to fish for Tilapia, a hardy fish whose effective breeding habits can lead to it overrunning native species, other noxious fish such as carp, and ornamental fish commonly kept in home aquariums such as goldfish. To take part in the fishing activity, residents are asked to sign up at the registration marquee near the Stage area at the parklands where they will be directed to one of the designated fishing sites around the lake.

There will also be a free sausage sizzle.

Participants will be required to bring along their own fishing rod and line. Barb-free hooks will be provided to reduce the impact on native bycatch that will be returned to the water. Bait will be available on site.

As this is an outdoors event, participants should also bring water, sun smart clothing, hat, sunscreen and enclosed shoes. All children, under the age of 18, must be accompanied by an adult.

Note: Fishing in Forest Lake is normally prohibited, however Council has approval to oversee this one off event to raise awareness for and manage this pest species.

Mozambique tilapia/mouthbrooder,Oreochromis mossambicus. Image: DAFF

Mozambique tilapia/mouthbrooder,Oreochromis mossambicus. Image: DAFF

More information about pest fish is available from the Department of Agriculture, Fisheries and Forestry.

May 072014

By Greg Wallis (pseudechis) at YouTube

The Barramundi or Giant Perch (Lates calcarifer) is an iconic fish from the freshwater billabongs, estuaries and coastline of northern Australia. Growing to 180cm and 60kg in size, these fish are a formidable predator.

Hatchling Barramundi are almost entirely males and spend their first year around mangroves and floodplain lagoons before moving further upstream into freshwater. At around 3 — 5 years of age and 60 — 80 cms the fish change sex and become female and move downstream to the tidal river mouths to breed.

Generally speaking it’s not a good idea to swim in natural waterways where Barramundi occur. Because they migrate from upstream freshwater areas down to the mouths of the rivers and back again, if you see Barramundi in a swimming hole it means that there are no substantial barriers downstream impeding their movement up from the coast, which also means Saltwater Crocodiles will have no problems in also accessing the area!

Barramundi are highly prized by fisherman both for their eating and fighting qualities. They are a very important food source for Aboriginal people and are regularly depicted in bark paintings and rock art.

For more information on Barramundi see the Fishes of Australia website…

CAAB Taxon Code: 37310006


May 072014

By Greg Wallis (pseudechis) at YouTube

This school of Northwest Glassfish (Ambassis sp.) was filmed in a rainforest spring tributary of the Finniss River near Batchelor in the Northern Territory of Australia. Although this species is very common it remains officially undescribed. At one stage it was referred to as Ambassis muelleri which is now a synonym of Ambassis agassizii, a fish found through much of the Murray River system much further south.

For information on Northwest Glassfish see the fact sheet at Aquagreen…

For information on a closely related species the Sailfin Glassfish, Ambassis agrammus see the Fishes of Australia website…

CAAB Taxon Code: 37310008 a closely related species

Filmed with a Gopro Hero HD1 camera with an “eye of mine” housing

May 062014

Press release by Fraunhofer-Gesellschaft

Empty nets and few species – environmental hormones are believed responsible for the diminishing numbers of fish. How damaging are these substances really, though? Studies that depict a complete picture of the lives of fish provide clues.


Flow-through facility at Fraunhofer IME. All test aquaria can handle adult animals as well as those at the larval stage. Photo: © Fraunhofer IME

Flow-through facility at Fraunhofer IME. All test aquaria can handle adult animals as well as those at the larval stage. Photo: © Fraunhofer IME

You cannot see, smell, or taste them – and yet, environmental hormones are components of many materials and products. They can be found for example in colorants and dyes, pesticides, cosmetics, plastics, and in pharmaceuticals. Environmental hormones are molecules that behave like hormones, because they resemble them in their structure. It has been suspected that the substances getting into an organism via the air, the skin, through foodstuffs, and through medications influence the human reproductive system and cause a reduction in the quality of spermatozoa, with an associated drop in male fertility. The animal world is affected as well. In addition to other factors, environmental hormones are believed responsible for the reduction in fish populations.

Life cycle studies with freshwater fish

Experts and scientists have been in disagreement for over two decades about whether fish stocks and amphibian populations are actually threatened by any stress from hormonally active substances in bodies of water, because the effects of the environmental hormones actually remain insufficiently understood. Researchers of the Fraunhofer Institute for Molecular Biology and Applied Ecology IME in Schmallenberg, Germany, want to shed light on this question. To investigate the effects of hormonally active substances on fish, the scientists have established and continually refined a model using life cycle studies of the zebrafish (Danio rerio), a freshwater fish. “Using the life cycle test, we can record all of the relevant aspects in the life of fish within a reasonable period of time,” says Matthias Teigeler, an engineer in the Ecotoxicology Department at IME. “These include the growth, the embryonic and especially the sexual development, as well as the animals’ ability to reproduce. Those are factors that react sensitively to hormonally active substances.”

Groups of like-sized fish are exposed to potentially active hormonal substances at differing concentrations while in a flow-through facility. A control group of fish kept in water with no hormone load serves as a comparison with which the possible effects on the subject animals can be discerned. “A life cycle test begins by employing fertilized eggs obtained from unstressed P generation (parental) animals. The fish embryos hatch three days later. We determine the number of surviving animals and record their lengths in the computer. After about three months, the animals are mature enough to be able to reproduce. Their ability to reproduce can be accurately determined from the number of eggs they lay. During the spawning phase, we remove eggs from the experimental aquaria each day and count them. Since they are transparent, you can examine whether they were fertilized or not,” explains Teigeler.

The researchers were actually able to determine that zebrafish were no longer able to reproduce – mating and deposition of eggs did not occur – under administration of very low concentrations of ethinyl estradiol, a synthetic estrogen and component of contraceptive pills. They observed negative effects with other substances under test as well. Tests with the synthetic sexual hormone trenbolone led to a masculinization of the animals, for example. The gender ratio shifted considerably. 100% of the fish developed as males following administration of the test substance. This could also be observed for aromatase inhibitors employed as a fungicide for plant protection. As a comparison, researchers would expect a gender ratio of 50 percent male to 50 percent female in the unstressed control group. “Several well-known substances negatively influence the hormone system. However, other factors besides hormonally active substances are under discussion as being responsible for the reduction in fish species, such as poorer constitution of waters and climate change,” says Teigeler.

Stricter approval requirements for manufacturers of plant protection products

Manufacturers of chemicals for protecting plants meanwhile anticipate being confronted with a prohibition if it turns out that an active ingredient causes a lasting disruption to the hormone system of humans and animals. Meanwhile, the pharmaceutical industry must likewise present data on the effects of hormone-like substances in bodies of water if they want to bring a new product out on the market in Europe. The testing system of Fraunhofer IME enjoys a high level of acceptance in industry as well as among regulatory authorities. Moreover, IME researchers offer support through their expertise with life cycle experiments, studies, and conclusions to committees of the OECD, the EU and their Member States having to develop guidelines for fish testing and to evaluate of test results. They help find answers to questions dealing with problems of hormonally active substances in the environment.

May 032014

The ConversationOriginal story by Tom Rayner, Charles Darwin University and Richard Kingsford at The Conversation

Wetlands and rivers need water – not least in the case of Australia’s biggest river system, the Murray-Darling Basin, which has been the target of an “environmental watering” plan designed to preserve its water levels and quality.
Water management in the Murray-Darling may be inadvertently helping the common carp at the expense of native fish. Photo: Tom Rayner

Water management in the Murray-Darling may be inadvertently helping the common carp at the expense of native fish. Photo: Tom Rayner

But our research shows that, during the 2010-11 floods, measures taken to manage water levels and preserve local wildlife ended up helping alien species, such as the troublesome common carp.

A helping hand for fish

Environmental watering programs are used worldwide to replenish previously degraded catchments. One of the ways to test how well they are working is to look at what happens to native fish. Our evidence suggests that efforts in the Murray-Darling, although on the right track, might need some refinement to ensure we help the right species.

The 2010-11 episode also highlights the difficulty of performing what amounts to “environmental triage” on degraded river systems such as the Murray-Darling, while still ensuring that everything stays in balance. Continue reading »