Blackwing Hatchetfish (Carnegiella schereri) Aquarium Glaser

Carnegiella schereri - Blackwing Hatchetfish

Carnegiella schereri is a small, peaceful freshwater hatchetfish native to South America. It’s best known for its upturned mouth, deep chest, and wing‑like pectoral fins, which allow it to launch itself out of the water to escape predators. This species is highly prized in the aquarium hobby for its subtle elegance and surface‑dwelling behavior.

It is sometimes confused with Carnegiella marthae or Carnegiella strigata, but C. schereri has distinctive darker pectoral fins (“black wings”) and a more delicate body pattern.

Natural Habitat

• Region: Amazon Basin (primarily Brazil, Colombia, Peru)
• Environment:
  • Slow‑moving streams
  • Flooded forest margins
  • Blackwater and soft clearwater tributaries
• Key features:
  • Dense overhanging vegetation
  • Leaf litter
  • Calm surface with minimal current

They spend nearly all their time at the surface, rarely venturing into mid‑water.

Physical Description

• Adult size: ~2.5–3.0 cm (≈1–1.2 in)
• Body shape: Strongly laterally compressed with a deep chest
• Coloration:
  • Silver to light bronze body
  • Darker lateral markings
  • Distinct dark/black pectoral fins
• Sexing:
  • Females slightly deeper‑bodied, especially when gravid
  • Otherwise difficult to distinguish

Aquarium Care

Tank Size

• Minimum: 10 gallons (38 L)
• Ideal: 15–20 gallons+ for a group
• A tight‑fitting lid is absolutely mandatory — they are exceptional jumpers.

Water Parameters

• Temperature: 24–28 °C (75–82 °F)
• pH: 5.0–6.8 (slightly acidic preferred)
• Hardness: 1–6 dGH (very soft)
• Flow: Gentle; avoid strong surface agitation

Stable, clean water is critical — they are sensitive to poor water quality.

Aquascaping Recommendations

• Floating plants (Salvinia, Amazon frogbit, water lettuce)
• Dim or filtered lighting
• Dark substrate to reduce stress
• Driftwood and leaf litter (Indian almond leaves are excellent)
• Open surface area for feeding

A blackwater‑style aquascape closely mimics their natural environment and improves coloration and confidence.

Diet

Carnivorous micro‑predator

Best foods:

• Live or frozen:
  • Daphnia
  • Cyclops
  • Artemia (baby brine shrimp)
  • Mosquito larvae
• High‑quality floating micro‑pellets or flakes (only once acclimated)

They feed exclusively at the surface, so sinking foods are usually ignored.

Behavior & Compatibility

• Temperament: Peaceful, shy
• Social needs: Keep in groups of 6–10+
• Tank mates:
  • Small, calm species only
  • Tetras, pencilfish, small Corydoras, dwarf rasboras
• Avoid:
  • Aggressive or fast‑moving fish
  • Loud surface feeders
  • Large cichlids or barbs

They are easily stressed by excessive activity near the surface.

Breeding Notes (Advanced)

• Rarely bred in home aquaria
• Requires:
  • Very soft acidic water
  • Heavy floating plants
  • Live foods to condition adults
• Eggs are small, adhesive, and deposited among surface plants
• Adults may eat eggs — separation is required

Common Issues

• Jumping (most common cause of loss)
• Refusal to eat prepared foods initially
• Stress from bright lighting or surface disturbance
• Poor acclimation to hard or alkaline water

Slow drip acclimation is strongly recommended.