Two-spined blackfish facts for kids
Quick facts for kids Two-spined blackfish |
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The two-spined blackfish (Gadopsis bispinosus) is a unique type of temperate perch fish. It lives only in Australia.
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Where the Two-Spined Blackfish Lives
This fish calls home the cool, clear, fast-flowing rivers and streams. These are found in the mountains of the southeastern Murray-Darling river system. You can find them in northeast Victoria, southeast New South Wales and the Australian Capital Territory. Long ago, two-spined blackfish shared these waters with other fish like Macquarie perch and trout cod.
What Does the Two-Spined Blackfish Look Like?
The two-spined blackfish looks a lot like its cousin, the river blackfish. The main difference is in its spiny dorsal fin (the fin on its back). The two-spined blackfish usually has only two spines. This is how it got its scientific name, bispinosus, which means "two-spined." River blackfish, however, have 7 to 13 spines in their dorsal fin.
Size and Preferred Habitat
Two-spined blackfish are smaller than river blackfish. They are usually about 15 to 17 centimeters long. The biggest ones can reach about 30 centimeters. While river blackfish like timber for their homes, two-spined blackfish prefer rocks. They like to hide and lay their eggs in the small gaps between rocks.
Diet and Reproduction
The two-spined blackfish mostly eats insect larvae that live in the water. They also munch on insects that fall into the water from land. Sometimes, they will eat other small fish or crayfish.
Life Cycle of the Blackfish
Two-spined blackfish breed between October and December. After about 16 days, the larvae (baby fish) hatch. They stay with their male parent at the spawning site for another three weeks.
Protecting the Two-Spined Blackfish
The number of two-spined blackfish has dropped a lot. This is mainly because of two big problems:
- Silt in rivers: When soil washes into rivers, it fills up the gaps between rocks. These gaps are where the blackfish hide from predators.
- Introduced fish: New types of fish, especially trout, have been brought into their habitats. These trout compete with the blackfish for food and also eat them.
Challenges for Survival
Even though trout are a threat, the two-spined blackfish can sometimes survive. They are active at night and good at hiding. This helps them avoid being eaten by trout.
However, recent big bushfires in southeastern Australia (from 2003 to 2006) caused a lot of silt to wash into the rivers. This filled up the rocky hiding spots. Scientists are worried that this will make it even harder for the blackfish to escape trout.
Blackfish species grow slowly and live a long time. They also don't travel far from their homes. This makes them very sensitive to overfishing and disappearing from certain areas. Their future is now a big concern.
