Rasbora tawarensis facts for kids
Quick facts for kids Rasbora tawarensis |
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| Conservation status | |
Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Cypriniformes |
| Family: | Cyprinidae |
| Subfamily: | Danioninae |
| Genus: | Rasbora |
| Species: |
R. tawarensis
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| Binomial name | |
| Rasbora tawarensis M. C. W. Weber & de Beaufort, 1916
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The Rasbora tawarensis, also known as depik, is a special type of fish. It is a critically endangered species, which means it is in great danger of disappearing forever. This fish lives only in Lake Laut Tawar in Indonesia. Sadly, its numbers are quickly shrinking. This is happening because of changes in its environment, global warming, new fish species, harmful fishing methods, and pollution.
Contents
What is the Depik Fish?
About 60 different kinds of Rasbora fish exist around the world. One of them is the Rasbora tawarensis, or depik. It is a freshwater fish, meaning it lives in lakes, small rivers, and even rice fields.
Depik fish look a lot like anchovies. They have small, oval-shaped bodies. Their backs are black, and their bellies are white. Depik also look similar to two other fish found in Lake Laut Tawar: Relo (Rasbora tawarensis) and Eas (Resbora argyrotaenia). All three are small, but depik have softer bodies and smaller eyes.
The depik fish is listed as "critically endangered" on the IUCN Red List. This is because it lives in a very small area. The number of depik caught by fishermen has dropped a lot. For example, in the 1970s, fishermen caught about 1.17 kg of depik per square meter. By 2009, this dropped to only 0.02 kg per square meter.
Where Does Depik Live?
Lake Laut Tawar is the biggest lake in Aceh Province, Indonesia. It covers an area of about 57 square kilometers. The lake is located high up in the Gayo plateau, about 1,200 meters above sea level.
This lake was formed by a volcano called Dorman. It is surrounded by the Bukit Barisan mountains, which reach up to 2,000 meters high. About 25 small rivers flow into the lake. The Peusangan River is the only river that flows out of it.
Forests used to surround the lake, but many trees have been cut down. Farms, rice fields, and towns around the lake also affect its environment. Lake Laut Tawar is very important to the local Gayo people. It provides clean water, water for farms, and fish.
Lake Laut Tawar's Environment
The water in Lake Laut Tawar has certain conditions that affect the fish living there.
Water Temperature
The average water temperature in Lake Laut Tawar ranges from about 19.35 to 21.55 °C. This was measured during the day at different depths.
| Depth (m) | T (°C) |
| 1 | 21.55 |
| 5 | 21.37 |
| 10 | 21.15 |
| 20 | 20.70 |
| 50 | 19.35 |
Fish grow best when the water temperature is between 20 and 30 °C. If the temperature gets too high, it can stress the fish. This also makes their bodies work harder.
Water Clarity
The water in Lake Laut Tawar is not very salty. Its electrical conductivity (EC) is between 181.37 and 205.01 μS. The water brightness level (WTL) is between 1.29 and 2.92 meters.
| Average DHL (μS) | Water brightness (m) |
| 188.20 | 2.27 |
| 181.37 | 1.79 |
| 205.01 | 2.92 |
| 192.53 | 2.06 |
| 191.131 | 1.29 |
Water brightness shows how deep sunlight can go into the water. This is important for tiny plants in the water that make their own food. When there are many particles or waste in the water, it becomes cloudy. This cloudiness, called turbidity, makes it harder for fish to find food.
The water in Lake Laut Tawar is often cloudy. This is due to waste from homes and other activities nearby. Also, there are no mangroves to help filter the water. Good water brightness for fish is usually more than 0.45 meters.
Water Chemistry
The chemical balance of the lake water is also important for fish.
| Chemical parameter | Value |
| pH | 8.22–8.41 |
| Dissolved oxygen (ppm) | 500–7.0 |
| Biological oxygen demand (BOD, ppm) | 0.62 – 1.11 |
| Chemical oxygen demand (COD, ppm) | < 5 |
| Nitrates (ppm) | 0–0.13 |
| Nitrides (ppm) | 0.001–00003 |
| Phosphates (ppm) | 0.12–1.31 |
| Potassium (ppm) | 1.93–2.15 |
Why is Depik Endangered?
The number of depik fish has dropped a lot. This is due to four main reasons: changes in the environment and global warming, new species of fish, harmful fishing, and pollution.
Even though the lake's temperature is still good for depik, global warming is slowly making it warmer. This could affect the depik's life cycle. Also, pollution in the lake is increasing. This area is growing fast and is a popular place for tourists.
New Species
New fish species brought into the lake are a big problem for depik. These new fish eat depik or compete with them for food. For example, a fish called Ikan Mas (Cyprinus carpio) is an invasive species. It has spread all over the lake.
Fishing Methods
Some fishing methods also harm the depik population. Local fishermen sometimes use a trap called "dedeseun." This trap catches depik as they swim into rivers to lay eggs. Many adult fish are caught this way. Some fishermen also use nets with very small holes (about 1.4 cm). These nets catch even small, young depik.
Where are Depik Found?
We do not have exact numbers for the current depik population.
Depik fish are found more often in certain parts of the lake. They are caught more in waters about ten meters deep. They are also found more about 100 meters away from the shore. Depik are caught in shallow water and near the shore too, but less often. Fishermen catch more depik during the rainy season than in the dry season.
