Ludwigia repens, commonly known as creeping primrose-willow or red ludwigia, is a popular aquatic plant often used in freshwater aquariums. Known for its attractive reddish-green leaves, it adds a vibrant splash of color and is relatively easy to care for, making it suitable for both beginner and experienced aquarists.

Here are some key points about Ludwigia repens:

1. Appearance: Ludwigia repens has lance-shaped leaves that can range in color from green to red, depending on the lighting and nutrient levels. The plant grows both horizontally and vertically, providing a lush, bushy appearance.

2. Lighting: Moderate to high lighting is recommended to bring out the red coloration in the leaves. Under low light, the plant tends to stay green and may not grow as vigorously.

3. Water Conditions: This plant thrives in a range of water conditions but prefers slightly acidic to neutral pH levels (6.0-7.5) and temperatures between 72-82°F (22-28°C).

4. Nutrients: Regular supplementation of nutrients, especially iron, will help maintain the plant’s health and coloration. CO₂ injection can also enhance growth and color, though it is not strictly necessary.

5. Propagation: Ludwigia repens can be easily propagated by cutting the stems and planting them in the substrate. The cuttings will develop roots and grow into new plants.

6. Placement: This plant is versatile and can be used as a midground or background plant in an aquarium. Regular trimming and maintenance are needed to prevent it from overshadowing other plants.

7. Compatibility: Ludwigia repens is compatible with most freshwater fish and invertebrates, making it a great addition to community tanks. However, it may be eaten by herbivorous fish such as goldfish.

If you need more specific information or have any questions about growing or caring for Ludwigia repens, feel free to ask!