Chelidonura varians - Neon Slug

The broad head shield, dark body, brilliant blue pattern and two elongated posterior tails make Chelidonura varians easy to recognise. The animal follows chemical trails produced by flatworms and consumes its prey with a suction-like proboscis.

Neon Slug is not a general clean-up-crew animal. It does not graze algae or accept ordinary fish, coral or invertebrate foods. It should be introduced only to an established aquarium containing a confirmed population of suitable flatworms.

Key features

• Striking black-and-blue sea slug
• Scientific name: Chelidonura varians
• Common names: Neon Slug and Blue Velvet Slug
• Family: Aglajidae
• Broad head shield and two elongated posterior tails
• Native to the tropical Indo-Pacific
• Specialised flatworm predator
• Particularly associated with red planaria control
• Does not necessarily consume every flatworm species
• Does not consume flatworm eggs
• Does not graze algae
• Does not accept ordinary aquarium food
• Peaceful and generally reef safe
• Requires a continuous supply of suitable prey
• May starve after the flatworms are eliminated
• Extremely vulnerable to pump and overflow intakes
• Sensitive to copper and medications
• Naturally short-lived
• Recommended for experienced marine aquarists

Care information

• Adult size: commonly approximately 4–7 cm
• Diet: selected small flatworms
• Activity: active during the day and at dusk
• Temperament: peaceful
• Reef compatibility: generally reef safe
• Care level: advanced
• Origin: Red Sea and tropical Indo-Pacific
• Recommended minimum aquarium volume: approximately 75 litres

Suggested water conditions

• Temperature: approximately 23–26 °C
• Specific gravity: approximately 1.023–1.026
• pH: approximately 8.1–8.4
• Alkalinity: approximately 7–11 dKH
• Ammonia: 0 mg/l
• Nitrite: 0 mg/l
• Flow: low to moderate and indirect
• Lighting: low to moderate
• Oxygenation: high

Flatworm-control use

1. Identify the flatworms as accurately as possible.
2. Siphon away large visible aggregations.
3. Avoid simultaneous chemical flatworm treatments.
4. Protect all pumps, overflows and filter intakes.
5. Acclimate the Neon Slug gradually.
6. Release it close to areas containing suitable flatworms.
7. Monitor hunting and movement.
8. Track the flatworm population over several weeks.
9. Remove dying or detached flatworms when possible.
10. Keep fresh activated carbon available.
11. Plan to transfer the slug before its food supply disappears.