Swan galaxias facts for kids
Quick facts for kids Swan galaxias |
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The Swan Galaxias (Galaxias fontanus) is a special type of fish. It belongs to the Galaxiidae family. This fish lives only in eastern Tasmania, Australia. It is found in the upper parts of the Swan and Macquarie River catchments. These areas are usually free of trout.
This brownish-olive fish prefers shallow streams that do not flow too fast. There are not many natural groups of these fish left. However, some have been moved to other streams where there are no predators.
Swan Galaxias fish are usually 7 to 13 centimeters long. They can weigh up to 8 grams. They are carnivores, meaning they eat meat. Their diet includes insects that live in water and insects that fall from land. These fish lay eggs during spring, usually from August to October. They can lay between 150 and 550 eggs. Each egg is about 2.2 to 2.5 millimeters wide.
The Swan Galaxias is listed as an Endangered species. This means it is at high risk of disappearing forever. Threats to this fish include other fish that eat them. Poor water quality, extreme weather, and human activities like agriculture and building dams also harm them. Groups like the World Wide Fund for Nature (WWFN) have helped fund efforts to protect them.
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What the Swan Galaxias Looks Like
Adult Swan Galaxias fish are about 7 to 13 centimeters long. They can weigh up to 8 grams. Their back and sides are a dark olive-green color. Their stomachs are a white-grey color. They have pale brown spots and irregular brown stripes on their sides and back.
The fish has a medium-sized tail fin that is forked. Its top fin (dorsal fin) is located above its vent. The fins on its chest (pectoral fins) are quite small. They reach about halfway back towards its belly fins (pelvic fins). All its fins are plain, without any marks. This fish does not have scales. Its body is covered by smooth skin. Its head is wide and a bit flat. Its eyes are located on the top of its head.
How it Got its Name
The scientific name for the Swan Galaxias is Galaxias fontanus. A fish expert named Wayne Fulton first found this species in 1978. He found it at Hardings Falls on the Swan River in eastern Tasmania.
The Swan Galaxias is a type of Actinopteri. This means its fins are supported by bony rays. It belongs to the galaxiiformes order and the galaxiidae family. These are freshwater fish found only in the Southern Hemisphere. Fulton chose the name "fontanus" for the fish. This word means "fast running" in Greek. It refers to the fast-moving river where the fish was found.
Where the Swan Galaxias Lives
Its Home Range
The Swan Galaxias lives only in eastern Tasmania. It is found in freshwater streams within the Swan River area. You can often find it in the upper parts of the Swan River. It especially likes small streams that flow into the main river (tributaries). Natural groups of Swan Galaxias live in the Upper Swan River, Blue Tier Creek, and Tater Garden Creek. This is because Hardings waterfall keeps other fish away. There are now nine groups of these fish that have been moved to other parts of the Swan River.
In 1864, brown trout (Salmo trutta) were brought into the Swan River area. These trout live downstream from Hardings Falls. Brown trout eat Swan Galaxias. This has forced the Swan Galaxias to live only in the upper parts of streams. We do not know how widely the Swan Galaxias lived before trout were introduced. However, some experts believe they were found throughout the entire river system.
Here is a list of places where the Swan Galaxias is found:
| Location | Distribution |
|---|---|
| Swan River | Natural |
| Lower Blue Tier Creek | Natural |
| Tater Garden Creek | Natural |
| St Pauls River | Moved by people |
| Dukes River | Moved by people |
| Tullochgorum Creek | Moved by people |
| Cygnet River | Moved by people |
| Coghlans Creek | Moved by people |
| Lost Falls Creek | Moved by people |
| Wye River | Moving failed |
| Upper Blue Tier Creek | Moved by people |
| Green Tier Creek | Moved by people |
| Rocka Rivulet | Moved by people |
What Its Home Looks Like
Swan Galaxias fish live only in freshwater streams. These streams flow into larger rivers. They are found in the very top parts (headwaters) of small streams. These areas are hard for other types of fish to reach. The streams where they live are shallow and do not flow too fast. They are often in forested areas. These spots have rocky pools and plants growing along the stream banks (riparian cover).
Baby fish (Larvae) and young fish (juveniles) swim in groups in open, slow-moving water. Adult fish live in slow-flowing pools. These pools have lots of plants both in and along the stream.
What the Swan Galaxias Eats
Adult Swan Galaxias fish eat whatever food they can find. They eat insects that live in water and insects that fall from land. They especially like adult land insects like ants, beetles, grasshoppers, and crickets. These insects often fall into the water from plants along the stream.
They also eat water insects such as stoneflies, dragonflies, and mayflies. Small planktonic crustaceans like water fleas, krill, and copepods are also on their menu. Baby and young fish eat algae. They find this algae on the rocky bottom of the stream.
Life Cycle and Reproduction
How it Makes Babies
Swan Galaxias fish usually start having babies in their second year of life. This often happens in April. They have a long spawning period that lasts about three months. This is during the spring season, usually from August to October. The fish lay their eggs in their usual habitat. They place the eggs among shallow rocks in both fast-moving and slow-moving water.
A female Swan Galaxias can lay between 150 and 550 eggs. Each egg is about 2.2 to 2.5 millimeters wide. It takes about five weeks for the larvae (baby fish) to develop. When the larvae grow to about 35 millimeters long, they start to get their adult colors. The Swan Galaxias usually lives for about three years.
In special fish farms, eggs that are fertilized by humans hatch in about 17 days. This happens when the water temperature is between 11.5 and 18.5 degrees Celsius.
Dangers to the Swan Galaxias
New Fishy Neighbors
The biggest danger to the Swan Galaxias is other fish that have been brought into their habitat. Brown trout (Salmo trutt) and redfin perch (Perca fluviatilis) have caused the Swan Galaxias population to shrink. Experts have even seen two local groups of Swan Galaxias disappear because of these new fish. These introduced fish have forced the natural groups of Swan Galaxias to live in small, separate areas. They are now found only in the upper parts of a few streams.
Dams and Their Impact
Building dams on creeks where Swan Galaxias live can cause problems. Dams can block the fish from moving around. They can also change how much water flows in the stream. This can make water levels go up and down. Dams can also harm the places where the fish lay their eggs. If there is less water flow, the rocky creek bottom where they lay eggs can become dry.
Water Quality and Plants Along Streams
Cutting down plants along streams for farming is a threat. Also, pollution from towns can make the water quality poor. Both poor water quality and fewer plants along the stream can affect where Swan Galaxias live. It can also reduce how many of them there are in the Swan River area.
Weather Worries
Changes in weather, like flooding and droughts, also affect the Swan Galaxias. Since these fish live in small streams at the top of rivers, changes in water levels are a big threat. Because the new, introduced fish live downstream, the Swan Galaxias cannot escape floods or droughts by moving to other areas. For example, floods in the Swan River in 2011 caused the Swan Galaxias population to drop by 74%.
Protecting the Swan Galaxias
Why it Needs Help
The Swan Galaxias is an Endangered species. This means it is at risk of disappearing. It is listed as Endangered by groups around the world, in Australia, and in Tasmania. It was listed as Endangered by the IUCN Red List and under the Environment Protection and Biodiversity Conservation Act 1999.
The Australian Federal Environment Protection and Biodiversity Conservation Act 1999 (EPBC) listed it as Endangered on November 10, 2006. Tasmania also protects the fish under its Threatened Species Protection Act 1995 (TSP). The fish is also a "priority species" under the Tasmanian Regional Forest Agreement 1997. This agreement helps protect the species through a special reserve system.
The Swan Galaxias is endangered for several reasons. These include its limited number and small living area. Its habitat is also being destroyed. And, other fish that eat them are a big problem. The Australian Government says the fish population has been shrinking for the last 10 years and continues to decline.
Since the fish was discovered, its natural living areas have become smaller and broken up. Only three groups of fish are left in a few streams. They are confined to the very top parts of these rivers.
Experts say that the small number of these fish is due to their habitat being damaged. This damage includes dirt building up in the water (sedimentation). It also includes poor water quality from towns, farms, and logging. Climate change is also a global threat. It causes water temperatures to rise. This means less water in the headwater streams where the Swan Galaxias lives. The fish needs specific water conditions to lay eggs. So, dams that take water away from their habitat have a big impact.
Other fish that eat or compete with the Swan Galaxias are also a reason for its endangered status. Since brown trout (Salmo trutt) and redfin perch (Perca fluviatilis) were introduced, the Swan Galaxias population has dropped. This is mainly because these fish cannot live in the same place due to fighting for food and being eaten.
Helping the Swan Galaxias
From 1987 to 1989, the World Wide Fund for Nature gave money to the Australian Fisheries Management Authority (AFMA). This money was for a detailed study of the Swan Galaxias. They looked at its life ecology, what it needs in its habitat, and where it naturally lives. The study found areas where the Swan Galaxias naturally lives. These areas were then named "Forestry Tasmania Wildlife Priority Areas." The project aimed to protect the species. It offered advice on how to manage the fish, which was used in a plan for Australian freshwater fish. This advice helped create the first recovery plan for the Swan Galaxias in 1993.
In 1987, some Swan Galaxias were moved to Blue Tier Creek. This was to see if moving them could help the species recover. One year later, a group of breeding fish was living there. This move was a success. So, in 1991, more fish were moved to Green Tier Creek and Lost Falls Creek.
In 1989, the Australian Government Department of Agriculture, Water and Environment fixed a natural barrier in Blue Tier Creek. They made the barrier taller and steeper. This was to stop trout from reaching the Swan Galaxias habitat. Since the barrier was improved, no trout have been seen upstream.
The first recovery plan was made in 1993. It described actions to move fish and build artificial barriers against other fish. The moved fish groups were watched to see if their numbers increased. The plan also aimed to create an education campaign. This was to improve the fish's conservation status. The AFMA put the plan's actions into place. The Endangered Species Program of Environment Australia (ESP) provided funding for five years.
From 2000 until now, a second recovery plan has been in action. Its goal is to make sure the first plan's efforts continue to work. It involves watching the population levels of the twelve groups of Swan Galaxias. The main goal of this plan is to get the Swan Galaxias moved from "Endangered" to "Vulnerable" status.
Images for kids
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The Swan Galaxias (Galaxias fontanus) is a small, unique fish.
