Azolla caroliniana

Scientific name: Azolla caroliniana

Family: Azollaceae

Maximum size reached under cultivation: 0 - 2 cm (0 - 0.79 inch)

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Recommended pH range: 6.3 - 8

Recommended water hardness: 0 - 18°dGH (0 - 321.43ppm)

0°C 32°F30°C 86°F

Recommended temperature range: 15 - 27 °C (59 - 80.6°F)

Preferred propagation method: Lateral shoots

Native to: North America

Growth rate: Normal

Recommended substrate: Without substrate

Lighting requirements: Bright

Ideal placement in tank: Floating

🌿 Common Names

Carolina Mosquito Fern, Water Velvet

🌍 Origin

Azolla caroliniana originates from North America, primarily found in freshwater habitats such as ponds, lakes, marshes, and slow-moving rivers. It is widespread across the southeastern United States and extends into parts of Central America. Outside its native range, it has spread to other continents and may behave invasively in non-native ecosystems.

⚡ Quick Overview

• Ideal For: Aquariums, ponds, wetlands, paludariums
• Difficulty Level: Easy
• Lighting: Bright to medium
• Placement: Floating only

💧 Growing Conditions

Azolla caroliniana is a floating plant that forms dense mats on the water’s surface. It absorbs nutrients directly from the water, making it ideal for nutrient control in aquariums and ponds. It thrives in still or slow-moving water with bright lighting for optimal growth, but can adapt to medium lighting with sufficient nutrients. Preferred temperature range is 15–27°C (59–80.6°F), and it tolerates soft to moderately hard water (0–18 dGH). No substrate is required.

📏 Planting Area

This is a true floating plant and should never be planted in the substrate. It floats freely on the water's surface and spreads naturally to cover aquariums, ponds, or paludarium surfaces. Individual plants are only a few millimeters in size, but colonies can form mats several centimeters thick.

🌱 Propagation

Azolla caroliniana primarily propagates vegetatively through fragmentation. As the plant grows, it produces lateral branches that break off and form new colonies. This allows rapid surface coverage in favorable conditions. Although it can also reproduce sexually via spores, vegetative growth is dominant in aquarium settings.

⚙️ Difficulty

Easy. This plant is low-maintenance, adaptable, and ideal for beginners. Regular thinning may be needed to prevent overgrowth, which could block light for submerged plants or lead to oxygen depletion at night in stagnant waters.

📝 Short Description

Azolla caroliniana is a fast-growing floating fern valued for its ecological benefits and ornamental use. It reduces nitrate levels by absorbing excess nutrients and limiting light penetration—thus helping control algae. It also serves as shelter for fish fry and as a natural fertilizer or fish food in certain cultures. However, if unmanaged, it can quickly cover the entire surface of a tank or pond.