The Common Hatchetfish Gasteropelecus sternicla is a most unusually shaped fish. Its body looks like the head of a hatchet, thus the common name "hatchetfish". The term Gasteropelecus actually means "hatchet-shaped belly".
The hatchetfishes of the family Gasteropelecidae leap from the water and fly through the air, flapping their large pectoral fins to catch flying insects. They are generally accepted as being the only true "flyingfish". There are a number of fish that can leap out of the water, but only these freshwater hatchetfish actually use their pectoral fins to aid in their flight.
The Common Hatchetfish is also called the River Hatchetfish as well as Silver Hatchetfish. The name Silver Hatchetfish is somewhat of a misnomer for this fish as there are a couple of other species also known by this common name. In the same genera there is the Silver Hatchetfish Gasteropelecus levis and there is another species of Silver Hatchetfish, Thoracocharax securis, which is also called the Greater Hatchetfish.
These hatchetfish are all very similar in appearance but they do differ in size. In the wild both the Gasteropelecus species are smaller, with the Common Hatchetfish reaching about 1.5 inches (3.8 cm) and G. levis reaching about 1 inch (3.5 cm). The Greater Hatchetfish grows much larger, getting up to 3 1/2" (9.1 cm) which is a full inch longer than the Common Hatchetfish. The Greater Hatchetfish also differs slightly in looks because it doesn't have the pronounced black horizontal line often seen on the Common Hatchetfish. The confusion is somewhat alleviated for the hobbyist because the Common Hatchetfish is the one most commonly sold as the Silver Hatchetfish.
These freshwater hatchetfish can fly a distance of more than 4 feet. Once they are in the air, they will move their pectoral fins like a bird's wings. The ability for the freshwater hatchetfish to fly is really astounding, but it is somewhat of a problem in the aquarium. The tank needs a tight fitting lid to keep these fish from leaping out of the tank to their demise.
Common Hatchetfish are very peaceful, and even timid fish. They make good community tank mates. They like to hang at the surface of the water and do appreciate some floating plants. But their mouth is situated up on top of their body and they eat at the surface, so be sure to also provide some clear areas as well for them to feed. They must be kept in a well maintained aquarium as they are prone to ich.
The Common Hatchetfish Gasteropelecus sternicla was described by Linnaeus in 1758. This species is not listed on the IUCN Red List. They are found in South America in Brazil and the southern tributaries of the Amazon. In Guyana and Surinam they are found in smaller streams with plenty of vegetation. Other common names they are known by are River Hatchetfish and Silver Hatchetfish.
In the wild they prefer areas that have an abundance of surface vegetation. They can be found at the surface most of the time, but will retreat occasionally if they feel threatened or when feeding. These fish can be seen almost flying for many feet out of the water to catch flying insects.
Scientific Name: Gasteropelecus sternicla
Social Grouping: Groups
IUCN Red List: NE - Not Evaluated or not listed
The Common Hatchetfish is a deep bodied fish with a 'hatchet' type shape to it. This fish will generally reach about 2 1/2 inches (6.5 cm) in length and has a lifespan of about 2 - 5 years. They will be more active and have the longer life span if kept in a good sized group, ideally with eight or more fish. They are basically a white or silvery looking color with a pronounced black horizontal line running through the center of the body. They have a mouth situated close to the top of their head for feeding at the surface.
This fish is sometime confused with its close relative the Silver Hatchetfish G. levi. However knowing what species you have is usually not to difficult for the aquarist as the Common Hatchetfish is a bit larger than the other, and it is also the one most commonly sold in pet stores.
Size of fish - inches: 2.6 inches (6.50 cm) - In the wild these fish only reach about 1 1/2 inches (3.8 cm), but aquarium specimens grow larger, reaching up to about 2 1/2 inches (6.5 cm).
Lifespan: 5 years - They have a life span of about 2 - 5 years. They will have a longer lifespan, and be more active, if kept in a group, ideally of 8 or more fish.
Fish Keeping Difficulty
The Common Hatchetfish is moderately hardy, but best suited for an aquarist with some fish keeping experience. They are very susceptible to Ich particularly when introduced to a new home. It is suggested that new purchases be acclimated in a quarantine tank.
Aquarium Hardiness: Moderately hardy - This fish is susceptible to ich, especially when first introduced to a new a aquarium.
Aquarist Experience Level: Intermediate
Foods and Feeding
These freshwater hatchetfish are carnivores that feed on crustaceans and insects in the wild. With their mouth situated up on top of their body they are used to eating surface foods such as small vinegar flies and mosquito larvae. In the aquarium the Common Hatchetfish will generally eat all kinds of live, fresh and flake foods as long as it is on the surface of the water. To keep a good balance give them a protein such as brine shrimp (either live or frozen), fruit flies, or blood worms everyday.
Diet Type: Omnivore - Their diet should be supplemented with live foods.
Flake Food: Yes
Tablet Pellet: Yes
Live foods (fishes, shrimps, worms): Some of Diet
Vegetable Food: Some of Diet
Meaty Food: Some of Diet
Feeding Frequency: Several feedings per day
Hatchtfish are not exceptionally difficult to care for once acclimated provided their water is kept clean. Aquariums are closed systems and regardless of size all need some maintenance. Over time decomposing organic matter, nitrates, and phosphate build up and the water hardness increases due to evaporation. To combat these ever changing conditions water should be replaced on a regular basis, especially if the tank is densely stocked. At least 25 - 50% of the tank water should be replaced every other week.
Water Changes: Bi-weekly
These fish are moderately hardy. A school of 6 or more fish will do best in about a 15 to 20 gallon aquarium. They will mostly swim and feed at the surface of the water. They will appreciate some floating plants, but as they eat at the surface some clear areas need to be provided as well. The tank should be tightly sealed as this fish is apt to jump out of the tank if provided the opportunity.
These freshwater hatchetfish are prone to ich, especially when first introduced to a new aquarium. It is suggested they be acclimated in a quarantine aquarium before being placed in their permanent home. This blackwater native is very intolerant of harder and more alkaline water. The water conditions should be kept soft and acidic for them to thrive. Peat filtration is advisable.
Minimum Tank Size: 15 gal (57 L)
Suitable for Nano Tank: Yes - A larger nano tank can be used to house a school.
Substrate Type: Any
Lighting Needs: Moderate - normal lighting
Temperature: 72.0 to 81.0° F (22.2 to 27.2° C)
Range ph: 6.0-7.5
Hardness Range: 2 - 15 dGH
Water Movement: Moderate
Water Region: Top - The Common Hatchetfish will swim at the top of the aquarium. Notice how the mouth is at the top of the body.
The Common Hatchetfish are generally a good community fish. This fish is relatively shy so it should be spared the company of hostile tank mates. It must absolutely be kept in a school. A minimum sized school would be 6 hatchetfish, but 8 or more are ideal. If provided a good sized school, they will be more active and have a longer lifespan. Good tankmates for this fish are tetras, dwarf cichlids and Corydoras and Loricariids.
Temperament: Peaceful - These fish are very nervous and timid so monitor interactions with other tankmates.
Same species - conspecifics: Yes - They must to be kept in a school. Six fish is minimum, but 8 or more is suggested.
Peaceful fish (): Safe
Semi-Aggressive (): Monitor
Aggressive (): Threat
Large Semi-Aggressive (): Threat
Large Aggressive, Predatory (): Threat
Slow Swimmers & Eaters (): Monitor
Shrimps, Crabs, Snails: Safe - not aggressive
Sex: Sexual differences
It is hard to tell, but if viewed from above the female is more plump.
Breeding / Reproduction
The Common Hatchetfish are egg layers, but they have not been successfully bred in captivity. Interestingly their cousin the Marbled Hatchetfish Carnegiella strigata, though not quite as hardy, will breed quite easily. For a description of breeding characin fish, see Breeding Freshwater Fish: Characins.
Ease of Breeding: Unknown
The Common Hatchetfish are prone to develop ick (ichthyobodo infection). This is especially true when first introduced to an new aquarium. Keeping a quarantine tank is suggested when first acquiring these fish. They are also susceptible if kept the tank water is not kept soft and acidic.
As with most fish these freshwater hatchetfish are prone to skin flukes, parasitic infestations (protozoa, worms, etc.), parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial disease. They are extremely hardy and disease is not usually a problem in a well maintained aquarium. That being said there is no guarantee that you won't have to deal with health problems or disease. Remember anything you add to your tank can bring disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance.
A good thing about the Common Hatchetfish is that due to their resilience, an outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. When keeping more sensitive types of fish, it is common for all fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your Common Hatchetfish the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. Stressed fish are more likely to acquire disease.
For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments. This is a great source for information on disease and treatments. It is recommended to read up on the common tank diseases. Knowing the signs and catching and treating them early makes a huge difference
The Common Hatchetfish is readily available. They are somewhat more expensive than their cousin the Marbled HatchetfishCarnegiella strigata, but are also a hardier species which makes them worth the extra price.
kye turnbull - 2013-05-14 my mum loves these fishes mouths! im going to get her some as present when i get my tetra tank!
Clarice Brough - 2013-05-14 They are very cool fish, and fairly hardy. Best to make sure you get enough of them though, and have plenty of space so they can get out of each other's way if one decides to be belligerent.
Gary A.MacDonald - 2010-04-21 While I was down collecting in Bolivia last year, I happened upon a large shoal of these in the Rio San Martin. I will have to say, the Wild living relatives of our Aquarium inhabitants can grow to huge proportions! Not only that, they really can skim across the water top to great lengths!
A tight fitting lid -- definitely, and if you have one, a Canopy even better.
sam - 2012-06-14 How big do they get?! They were breed down alot I guess so they could be sold in stores