Blackwing Hatchetfish – Carnegiella marthae
The Blackwing Hatchetfish (Carnegiella marthae) is a small, peaceful freshwater fish known for its distinctive hatchet-shaped body, silver coloration, dark markings, and wing-like pectoral fins.
This South American species spends nearly all of its time close to the water surface and is best kept in a peaceful, mature aquarium with floating plants, gentle water movement, and a securely fitted lid.
Key Features
- Distinctive hatchet-shaped body
- Silver coloration with dark black markings
- Very small adult size
- Peaceful freshwater species
- Surface-dwelling fish
- Best kept in groups
- Excellent choice for soft-water planted aquariums
- Requires a tightly fitting aquarium lid
Fish Information
- Common Name: Blackwing Hatchetfish
- Other Trade Names: Black Wing Hatchetfish, Black Hatchet Wing
- Scientific Name: Carnegiella marthae
- Family: Gasteropelecidae
- Origin: South America
- Native Range: Negro and upper Orinoco River drainages
- Water Type: Freshwater
- Temperament: Very peaceful
- Adult Size: Approximately 1–1.4 inches
- Swimming Level: Surface / upper level
- Diet: Carnivorous / insectivorous omnivore
- Care Level: Moderate
Adult Size
Blackwing Hatchetfish are among the smallest freshwater hatchetfish species.
They generally remain around 1–1.4 inches in total length. FishBase reports a maximum standard length of approximately 2.9 cm, with aquarium specimens reaching around 3.5 cm total length.
Recommended Group Size
Blackwing Hatchetfish are highly social fish and should not be kept alone.
A group of at least 6 is recommended, while groups of 8–10 or more are even better when aquarium space allows.
Larger groups generally produce more confident behavior and a more natural surface-schooling display.
Recommended Aquarium Size
A 15–20 gallon aquarium or larger is recommended for a group of Blackwing Hatchetfish.
Horizontal surface area is particularly important because these fish spend most of their time near the top of the aquarium.
Recommended Water Parameters
- Temperature: Approximately 68–82°F
- pH: Approximately 4.0–7.0
- Water Hardness: Soft, approximately 1–10 dGH
- Ammonia: 0 ppm
- Nitrite: 0 ppm
- Nitrate: Kept low through regular maintenance
Blackwing Hatchetfish naturally inhabit soft, acidic blackwater environments and generally do best when maintained in relatively soft water with stable parameters.
Aquarium Setup
A planted aquarium with shaded areas and floating vegetation is ideal for this species.
- Use a mature, fully cycled aquarium
- Provide gentle to moderate filtration
- Maintain good oxygenation
- Add floating plants for shade and security
- Use driftwood or branches to create a natural appearance
- Consider dried leaves for a blackwater-style setup
- Leave some open surface area for swimming and feeding
- Use a tightly fitting aquarium lid
Important Lid Requirement
A securely fitted lid is essential.
Hatchetfish are powerful jumpers, and even small openings around filters, plumbing, or cables may allow them to escape.
Check the aquarium lid carefully for gaps before adding Blackwing Hatchetfish.
Feeding
Blackwing Hatchetfish naturally feed primarily near the water surface on small insects, aquatic invertebrates, and zooplankton.
Suitable aquarium foods include:
- Quality floating flakes
- Small floating or slow-sinking micro pellets
- Baby brine shrimp
- Frozen or live daphnia
- Moina
- Small frozen foods
- Small cultured insects such as fruit flies
Because they spend almost all of their time near the surface, food should remain near the upper portion of the aquarium long enough for them to feed comfortably.
Temperament
Blackwing Hatchetfish are extremely peaceful and somewhat timid.
They are best housed with small, calm community fish that will not outcompete them for food or harass them at the surface.
Compatible Tankmates
Suitable tankmates may include:
- Small peaceful tetras
- Small rasboras
- Corydoras
- Small peaceful plecos
- Apistogramma and other peaceful dwarf cichlids
- Other calm soft-water community species
Avoid large, aggressive, or extremely active fish that may intimidate or consume these small hatchetfish.
Blackwater Aquarium
Blackwing Hatchetfish are particularly well suited to natural-style blackwater aquariums.
A blackwater setup may include:
- Driftwood
- Dried botanical leaves
- Floating plants
- Dim lighting
- Soft, acidic water
- Dark substrate
The tannin-stained water and shaded environment can closely resemble their natural habitat.
Plants and Aquascaping
Floating plants are especially useful because Blackwing Hatchetfish naturally gather around vegetation near the surface.
Suitable plants may include:
- Amazon Frogbit
- Salvinia
- Red Root Floaters
- Water Sprite
- Anubias
- Java Fern
- Cryptocoryne
Leave areas of open surface water so the fish have room to swim and feed.
Breeding
Captive reproduction of Carnegiella marthae is uncommon and is not well documented compared with many commonly bred aquarium fish.
Maintaining mature fish in excellent condition with soft, acidic water and a varied diet may encourage natural reproductive behavior, but this species should not be considered an easy breeding fish.
Important Care Notes
- Keep in groups rather than individually.
- Provide a mature and stable aquarium.
- Soft, acidic water is preferred.
- Use floating plants for security.
- Feed foods that remain near the surface.
- Avoid large or aggressive tankmates.
- Keep ammonia and nitrite at 0 ppm.
- Use a tightly fitted lid with no escape gaps.
- Never release aquarium fish into local waterways.
Frequently Asked Questions
How large do Blackwing Hatchetfish get?
They are very small fish, generally reaching only about 1–1.4 inches in total length.
How many Blackwing Hatchetfish should I keep?
At least six are recommended, although groups of eight to ten or more are preferred when space allows.
Are Blackwing Hatchetfish peaceful?
Yes. They are very peaceful and somewhat timid, making them best suited to calm community aquariums.
Do Blackwing Hatchetfish jump?
Yes. They are capable of powerful jumps, so a tightly fitting aquarium lid is extremely important.
Where do they swim in the aquarium?
They spend nearly all of their time at or immediately below the water surface.
Do they need floating plants?
Floating plants are strongly recommended because they provide shade and security and closely resemble the fish's natural habitat.
Can they live with dwarf cichlids?
Yes. Peaceful dwarf cichlids such as Apistogramma can work well because they occupy different areas of the aquarium.
Are they good beginner fish?
They are better suited to aquarists with some experience because they are small, somewhat delicate, prefer soft stable water, and require careful attention to escape-proofing the aquarium.
Available at Tropical Treasures Wyo
Blackwing Hatchetfish are available at Tropical Treasures Wyo in Cheyenne, Wyoming, when in stock.
Live fish are available for in-store purchase or local pickup only and are not available for shipping.
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