Helfrich’s Firefish (Nemateleotris helfrichi)
• Small fish safe: ✅ Yes
• Small invert safe: ✅ Yes
• Coral safe: ✅ Yes
• Minimum tank size: 75 liters (20 gallons)
• Adult size: Up to 6.5 cm (2.5 inches)
• Diet: Carnivorous, primarily feeding on zooplankton
• Be aware of: Highly prone to jumping, requiring a secure lid; extremely shy, especially when first introduced; prefers low aggression tank mates
Appearance and Coloration
Helfrich’s Firefish is one of the most stunning and sought-after species of dartfish. Its body features a pastel blend of purple, lavender, yellow, and white, with a bright yellow face that transitions into a pale violet body. The dorsal fin is elongated and often displayed when alert, giving the fish an elegant and regal appearance.
Natural Habitat and Behavior
In the wild, Nemateleotris helfrichi inhabits deepwater reefs, often found at depths between 40 to 90 meters (130 to 295 feet). Due to their natural deepwater environment, they prefer dimmer lighting and subdued water movement compared to their relatives, N. magnifica and N. decora.
They are generally shy and will spend time hovering above their chosen hiding spots, darting into crevices when threatened. They do best in aquariums that provide a sense of security with rock caves and overhangs.
Tank Requirements and Water Parameters
• Minimum Tank Size: 20 gallons (75 liters) for a single specimen; larger tanks required for pairs or groups.
• Water Parameters:
• Temperature: 24°C – 27°C (75°F – 81°F)
• pH: 8.1 – 8.4
• Specific Gravity: 1.020 – 1.025
• Aquascaping:
• Provide plenty of live rock with crevices for shelter.
• Fine sand substrate is ideal.
• Open swimming space is necessary for them to hover comfortably.
• Lighting: Moderate to dim lighting mimics their natural deepwater habitat.
• Water Movement: Gentle to moderate flow; they do not do well in high currents.
• Tank Cover: A tight-fitting lid is crucial, as they are extremely prone to jumping.
Diet and Feeding
Helfrich’s Firefish are micro-carnivores, feeding primarily on planktonic organisms in the wild.
• Natural Diet: Zooplankton and small invertebrates.
• Captive Diet:
• Mysis shrimp
• Brine shrimp
• Copepods
• Finely chopped seafood (fish, shrimp)
• High-quality marine flakes and pellets
Feed small portions 2-3 times per day to keep them well-fed and healthy.
Compatibility and Social Structure
• Temperament:
• Extremely peaceful, making them ideal for community reef tanks.
• Best kept singly or in bonded pairs; groups can be kept in very large tanks with adequate space.
• Tank Mates:
• Ideal companions include peaceful fish like small wrasses, gobies, and clownfish.
• Avoid aggressive or fast-moving species like dottybacks, large angelfish, or triggerfish.
• Reef Compatibility: 100% reef-safe—does not bother corals or invertebrates.
Important Considerations
• Jumping Behavior: Extremely prone to jumping, even more so than other Firefish species. A covered aquarium is mandatory.
• Shyness: May be very timid when first introduced. Ensuring plenty of hiding spots will help them adjust.
• Tank Stability: Prefers mature aquariums with stable water conditions.