algae

Planaria Infestation

Small flatworm pests that multiply rapidly in aquariums. Harmless to adult fish but can attack shrimp fry and compete for food. Often a sign of overfeeding.

Symptoms

Small flatworms with arrow-shaped heads crawling on glass, substrate, plants, and hardscape.
Clusters of them near food after feeding, especially in overfed tanks.
Shrimp fry may disappear or be attacked — planaria can prey on newborn shrimp.

Common Causes

Overfeeding leaves uneaten food and detritus that sustain planaria populations.
Introduction on live plants, new substrate, or unquarantined animals.
Protein-rich foods that also feed the worm population.

What to Check

Feed less and remove uneaten food within minutes — planaria thrive where food remains.
Vacuum the substrate and rinse filter media to reduce the detritus layer.
Inspect new plants and decor for tiny arrow-headed worms before adding them.

What Not to Do

Do not expect planaria to vanish while overfeeding continues — they are usually a sign of excess food.
Do not use copper-based or deworming products in a shrimp tank unless confirmed shrimp-safe.

This guide is informational and does not replace professional veterinary advice. If fish are severely ill, consult a veterinarian.

Planaria Infestation

Symptoms

Common Causes

What to Check

What Not to Do

Cookie Preferences

Planaria Infestation

Symptoms

Common Causes

What to Check

What Not to Do