Myriophyllum spicatum, commonly known as Eurasian Watermilfoil, is a submerged aquatic plant species found in freshwater environments. It is valued for its attractive feathery foliage and its ability to provide habitat for aquatic organisms. Here is a detailed description and care guide for Myriophyllum spicatum:

Description:

Myriophyllum spicatum has a distinctive appearance with long, slender stems covered in feathery, finely divided leaves. The leaves are arranged in whorls around the stem, creating a dense and bushy appearance.
The foliage is typically green, but it can exhibit reddish or purplish tones under certain conditions. The plant can grow up to several feet in length, and it forms dense underwater colonies.

Care Guide:

Lighting: Myriophyllum spicatum prefers moderate to high lighting conditions. Provide at least 2-3 watts per gallon of full-spectrum light to promote healthy growth.

Water Parameters: Maintain a water temperature between 20-28°C (68-82°F). The pH level should be slightly acidic to slightly alkaline, ranging from 6.5-8.0. Myriophyllum spicatum can tolerate a wide range of water hardness.

Substrate: It can root in various substrates, including gravel, sand, or mud. A nutrient-rich substrate can promote better growth and development.

Nutrient Requirements: Myriophyllum spicatum benefits from regular nutrient supplementation, particularly with iron and micronutrients. Liquid fertilizers or root tabs can be used to provide essential nutrients.
Carbon dioxide (CO2) supplementation is not necessary, but it can enhance growth if desired.

Water Flow and Oxygenation: Moderate water flow is beneficial for Myriophyllum spicatum, as it helps distribute nutrients and prevents stagnant conditions. It also aids in oxygenation of the water, which is important for the health of fish and other aquatic organisms.

Propagation: Myriophyllum spicatum can propagate through stem fragments or lateral shoots. Simply trim the healthy stems and replant them in the substrate, allowing them to establish new roots. Regular pruning is necessary to control the growth and prevent the plant from becoming too dense.

Compatibility: Myriophyllum spicatum is compatible with a wide range of fish and invertebrates. It provides cover and shelter for small fish and serves as a spawning substrate for some species. However, ensure that it does not overgrow and shade other plants in the aquarium.

Note: Myriophyllum spicatum is known to be an aggressive grower in some areas and can become invasive if not properly managed. It is important to check local regulations and guidelines before introducing it into natural water bodies.

Overall, Myriophyllum spicatum is a visually appealing submerged aquatic plant that adds beauty and habitat complexity to aquariums. With appropriate lighting, water conditions, and care, it can thrive and contribute to a healthy aquatic ecosystem.