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PlanteasyFreshwater

Hydrilla

Hydrilla verticillata

Hydrocharitaceae

📍 Asia (Southeast and South Asia, including India, Korea, Japan, and Australia); now invasively established across North America, Europe, Africa, and beyond

Hydrilla verticillata is a submerged aquatic plant with slender, branching stems densely covered in small, serrated, whorled leaves typically arranged in groups of 4-8, giving it a feathery, bright green appearance that can serve as a lush background plant in aquariums. It grows rapidly and provides excellent cover for fish and invertebrates, and can help with nutrient export in heavily stocked tanks. WARNING: Hydrilla is one of the world's most aggressive aquatic invasive species — it must never be released into natural waterways, ponds, or any outdoor water body, as even tiny fragments can establish and devastate native ecosystems.

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Common Diseases

Algae Overgrowth (Hair/Thread Algae)

Symptoms

Fine green or brown filamentous algae coating stems and leaves, reducing light penetration and smothering growth

Treatment

Reduce photoperiod, improve water circulation, introduce algae-eating invertebrates such as Amano shrimp or Nerite snails, and ensure nutrient balance

Nutrient Deficiency (Iron/Micronutrient)

Symptoms

Yellowing of young leaves (chlorosis), pale or translucent new growth, stunted development

Treatment

Dose a comprehensive liquid micronutrient fertilizer containing chelated iron; ensure adequate lighting for nutrient uptake

Melting / Stem Rot

Symptoms

Lower stems become soft, brown, and mushy; leaves drop from the base upward, often following a sudden change in water parameters

Treatment

Remove affected stems immediately, improve water flow around the base of plants, trim healthy tops and replant, and stabilize water parameters gradually

Snail Infestation

Symptoms

Visible grazing damage on leaves, holes or ragged edges, rapid decline in plant density alongside visible pest snail populations

Treatment

Manual removal, introduce assassin snails (Clea helena) to control pest snail populations, or use a snail trap; avoid chemical treatments in shrimp tanks

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Quick Facts

co2
Not required
light
Low to High (15-80+ PAR); adapts well to a wide range of intensities, grows fastest under high light
placement
Background; grown rooted in substrate or left floating, stems can be trimmed and replanted to maintain density
substrate
Adaptable; grows in sand, gravel, or nutrient-rich aquasoil; can also grow unrooted or floating
growth rate
Fast
propagation
Stem cuttings root readily; also spreads via turions (dormant buds) and rhizome fragments; simply cut and replant stem sections

Water it likes

ph
6.0-8.5
hardness
2-20 dGH
temperature
50–86°F (10–30°C)

Legality

Federal noxious weed — illegal to import or move across state lines in the U.S.

Not legal advice, and possibly incomplete or out of date. Rules vary by state and locality and change over time — always confirm the current regulations with your state wildlife or agriculture agency before buying, keeping, or shipping this species.

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