Torrentfish facts for kids
Quick facts for kids Torrentfish |
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| Conservation status | |
| Scientific classification | |
| Genus: |
Cheimarrichthys
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| Species: |
fosteri
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The torrentfish (Cheimarrichthys fosteri), also called panoko by Māori people, is a special freshwater fish. It lives only in New Zealand. Torrentfish are amazing at living in shallow, fast-moving parts of rivers called riffles and rapids. They can grow up to 20 centimeters (about 8 inches) long. Most often, they are about 10 to 12 centimeters (4 to 5 inches) long. These fish are amphidromous, which means they move between fresh water and the sea during their lives.
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What Does a Torrentfish Look Like?
Torrentfish have a strong body. Their underside is flat, and their back is curved. They have a wide head that tapers downwards, with eyes set high up. Their lower jaw is very far back, and a fleshy upper lip surrounds it. This special mouth helps them pick small bugs off the surface of stones.
Their fins are very strong. The two large, triangular pectoral fins are angled. This angle helps water flow over them, pushing the fish down onto the riverbed. This keeps them steady in fast-moving water. Their pelvic fins are located under their head. The dorsal and anal fins are very long. The dorsal fin stretches for almost half of the fish's body length. The tail fin is short and either flat or slightly forked. This shape is good for quick bursts of swimming, not for long, steady swims.
All torrentfish have a similar pattern. They have five dark stripes on a lighter background. Three stripes are on their body, usually angled downwards towards the head. A fourth stripe is vertical at the base of their tail. The fifth stripe goes through their eyes and angles down towards their pectoral fin.
Their color can be dark grey on a lighter grey background, or dark brown on a lighter brown background. Their color changes to match their surroundings. This helps the torrentfish blend in with the stones in their habitat, making them hard to spot.
Where Do Torrentfish Live?
Torrentfish mostly live in shallow, fast-flowing riffles and rapids. They do not spend much time actively swimming against the fast water. Instead, they live among and under loose gravel and small rocks. They come out from these hiding spots at night to find food.
Torrentfish usually live alone. They are also benthic, meaning they live on the bottom of the river. But if there are many of them, you might find them close together. Since part of their life cycle is spent in the sea, you will find more torrentfish closer to the coast.
They prefer gravelly rivers, especially braided rivers. These rivers have wide, open channels. Torrentfish like rivers where the gravel often moves. This movement keeps open spaces around and under the stones. These spaces are perfect for the torrentfish to hide from strong currents. Even though they are strong swimmers, they are not good climbers. So, you will only find them far inland if the river is not too steep and has no barriers like waterfalls.
Life Cycle of the Torrentfish
Torrentfish are amphidromous. This means their babies (called fry) go to the sea after hatching. Then, when they are a bit older (juveniles), they return to fresh water. There, they grow into adult fish.
Female torrentfish are found further upstream than males. Some females can be found as far as 235 kilometers (about 146 miles) from the sea. However, there is a large area where both males and females live together.
Female torrentfish swim downstream during summer and autumn when they are ready to lay their eggs. After laying eggs, they swim back upstream. They likely lay their eggs in the lower parts of rivers. The fry hatch and swim out to sea in late summer and autumn. They return to fresh water a short time later, in late autumn and winter. Because they must spend time in the sea, torrentfish cannot live in lakes that are completely cut off from the ocean, unlike some other New Zealand native fish.
Conservation Status
Torrentfish need a special home with cool, fast-flowing water that has lots of oxygen. Because of this, they are at risk from several things. In 2014, the New Zealand Department of Conservation said the torrentfish was "At Risk: Declining." This means their numbers are going down. The IUCN also called the torrentfish "Vulnerable" in 2014.
Threats to torrentfish include:
- Water being taken from rivers for farming (irrigation).
- Water pollution.
- Climate change, which can make waters warmer.
- River sedimentation. This happens when too much dirt and sand settle in the river. Torrentfish need loose gravel to live among. If the riverbed becomes too hard and compacted, they cannot find good places to hide.
See also
In Spanish: Paanokunoku para niños
