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Plant guide · Submerged plants

Brittle naiad (Najas minor)

An introduced naiad: a fine, much-branched underwater plant with narrow leaves in bundles. It breaks apart easily and comes back each year from seed.

Also called: brittle waternymph

A brittle naiad plant underwater, bushy with narrow leaves, above a sandy bottom.
Brittle naiad growing underwater. Photo: Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0 (source)

What it looks like

  • Fine stems with many branches and bundles of thin leaves along them (Penn State's description of naiads).
  • Very small teeth along each leaf edge, visible up close.
  • Can grow short and bushy or tall and slender.
  • Dies back each fall and returns from seed; fragments easily when pulled.
  • Telling brittle naiad from Pennsylvania's native naiads takes a close look; ask Penn State Extension or a lake consultant to confirm.

Easily confused with

  • Native naiads (several species).
  • Coontail and watermilfoils have different leaf shapes.

Good and bad for your pond

  • Naiads are an important waterfowl food and good underwater cover.
  • Heavy growth limits pond use and can cause oxygen drops and fish kills when it dies in fall.

Native or invasive?

Invasive in Pennsylvania

Introduced; on DCNR's invasive list. Introduced to North America (USDA PLANTS) and listed by DCNR as a lesser-threat invasive (rank 3).

USDA PLANTS: NAMI (lower 48 states: introduced)

Do grass carp eat it?

Grass carp eat it

PFBC lists naiad among grass carp's preferred foods; Penn State calls grass carp an excellent control for naiad. Grass carp prefer submerged plants like pondweeds, elodea and coontail; they rarely control algae mats or lilies.

Checked Oct 4, 2026 · Source: Using Grass Carp to Control Aquatic Plants (updated May 19, 2025) This may be outdated

Control options

Prevention first

Penn State Extension's advice for every nuisance plant and algae problem starts with nutrients: overgrowth is a symptom of excess phosphorus and nitrogen from sources such as barnyards, crop fields, septic systems, lawns and golf courses. Cutting fertilizer near the pond, maintaining septic systems, diverting nutrient-rich runoff and keeping a vegetated buffer strip are the long-term fixes; without them, control becomes a yearly chore.

Checked Oct 4, 2026 · Source: Filamentous Algae (updated May 19, 2025) and the companion Penn State plant fact sheets This may be outdated

Remove it by hand or machine

Harvesting is risky because fragments regrow. A drawdown helps somewhat, but the seeds tolerate cold.

Biological options

Grass carp, with a PFBC permit: PFBC grass carp permit needed for each waterbody before buying or stocking; $85 fee, returned if denied.

Checked Oct 4, 2026 · Source: 58 Pa. Code § 71a.10, Triploid grass carp This may be outdated

Chemical options (permit first)

Any herbicide or algaecide in a pond needs a joint DEP/PFBC Chapter 91 permit first, at any amount. Only products registered with the U.S. Environmental Protection Agency and with the Pennsylvania Department of Agriculture, and labeled specifically for aquatic use, can be listed on the Chapter 91 permit application. Treat in sections, early in the season: decaying plants can strip oxygen and kill fish.

Checked Oct 4, 2026 · Sources: Water Quality Permitting for Pesticide Applications in Pennsylvania: FAQ (rev. Feb 21, 2025), FAQ #2, #3, #8, #10, #11, #28, #29; Permit Requirement for Use of an Aquatic Herbicide in Ponds (updated Sep 8, 2025); Pond Management (FAQ: controlling submerged vegetation) This may be outdated

Follow the product label; the label is the law. A Chapter 91 permit is required before any herbicide or algaecide goes in a pond (see fact). Consider a licensed applicator.

Report it

Report a suspected aquatic invasive species, such as hydrilla or European water chestnut, to the Pennsylvania Fish and Boat Commission with its online form or the Pennsylvania Invasive Species Reporting hotline (1-833-INVASIV), or through PA iMapInvasives. A photo and the exact location help staff confirm it.

Checked Oct 4, 2026 · Source: Report Aquatic Invasive Species (AIS) This may be outdated

PFBC: Report aquatic invasive species PA iMapInvasives

Sources

Checked Oct 4, 2026