Few people know about the amazing little freshwater flying fish, better known as the hatchetfish. Likewise, many aquarists who keep these popular fish have also never learned of their flying ability, which is really quite remarkable for their small size. In nature, hatchetfish make long, gliding flights using their powerful “wing-like” fins to fly over the top of the water. In captivity, these beautiful fish can live in a home aquarium but will not attempt to fly.
COMMON NAMES: Marbled hatchetfish
SCIENTIFIC NAME: Carnegiella strigata
ADULT SIZE: 1 to 1.4 inches
LIFE EXPECTANCY: 5 years
|Origin||Bolivia, Brazil, Peru, Columbia|
|Minimum Tank Size||30-gallon|
|Breeding||Egg scatterer among surface roots|
|Care||Intermediate to advanced|
|pH||4.0 to 7.0|
|Hardness||4 to 2 dGH|
|Temperature||78 F to 82 F|
Origin and Distribution
Of the genus commonly referred to as hatchetfish, a total of three species are known, Carnegiella myersi, Carnegiella marthae, and Carnegiella strigata. Only Carnegiella strigata is commonly known and represented by not less than five sub-species, which are commonly seen today in aquarium stores.
The hatchetfish originates in the marshes, flooded regions, brooks, ditches, and in the small and large rivers all over The Guianas in northern South America. It is especially common in the jungle streams of the central and lower parts of the Amazon River basin.
Hatchetfish dwell immediately beneath the surface of the water where they like to hide among marsh and water plants and elevated roots. Groups shoal together as they continually search for larval insects and small aquatic invertebrates. When a larger fish approaches to prey upon them, the hatchetfish are in the air and far away from danger in an instant.
Colors and Markings
Hatchetfish get their name from their peculiar shape. From the side, they look like triangles that are rounded only at the bottom, not unlike the shape of a hatchet. From the front, they are thinner than a cracker, tapering to a wedged knife-edge along the belly. The disproportionately deep body contains large muscles that contribute to the fish’s ability to flap its fins in flight.
In the marbled hatchetfish, the basic coloration is brownish to golden yellow with a silver sheen; the back is dark green with black dots of varying size. The flanks are covered with a pattern of spots typically of a pink to brown color, changing to light blue. A pair of dark stripes may be seen on the sides of the head; a black lateral line, bordered on the upper side by a gleaming silver stripe runs from the gill covers to the caudal fin.
From the edge of the belly run three irregular dark blue to brownish-black stripes angling forward and backward across the body. The streak lying above the anal fin is also blackish. The fins are light greenish and transparent. The caudal fin is clearly green.
Hatchetfish are shoaling fish, which means they like to be kept in a group of 10 or more. Any skirmishes in the group are only a form of play, and no harm ever comes of it. They are very tolerant of bottom dwellers and can be kept without danger among quiet and mild-mannered species of fish of about the same size.
Hatchetfish Habitat and Care
After about 48 hours of thwarted attempts, captured wild hatchetfish will never attempt flight again. It is truly unfortunate that we do not get to see these fish fly in the aquarium, but they have been bred in captivity for so many generations that they have lost the will to even attempt the feat even when startled from below.
This fish is an inhabitant of exclusively blackwater environments. They prefer fallen branches, live plants, rock outcroppings and require room to swim in and around them. Putting these unique fish in a bare tank will make them feel very vulnerable and insecure; they will not long survive.
Hatchetfish are a very popular addition to aquariums, however, it is important to remember that this is fish that lives under the forest canopy. Provide a large aquarium with subdued or dimmed LED lighting. Use plant species that grow up to the surface of the water to simulate their natural environment. Use a dark substrate to simulate the river bottom.
It is unlikely that the fish that you buy in local stores and bred in captivity would try to fly, but do not take the chance; it has been known to happen. It should go without saying that any aquarium containing hatchetfish should be covered with a full aquarium hood to avoid unscheduled flights.
Hatchetfish Diet and Feeding
In nature, they are insect eaters and larva eaters taking terrestrial and aquatic invertebrates and other zooplankton taken at or near the water surface. They are very effective in keeping mosquito populations down.
In the aquarium, it will accept dried foods of a suitable size but should also be offered regular meals of small live and frozen fare such as Artemia nauplii, Daphnia, Moina, or grindal worms. Drosophila fruit flies or other young insects you can raise in bulk can also be fed, although it’s best to fill the stomachs of these insects (bio-loading) by feeding them fish flakes and vegetable matter before offering them to the fish.
External sexual characteristics are unknown. Some specimens do grow larger and fuller-bodied than others and are likely adult females. There are slightly different strains of color lines, part due to inbreeding, and partly due to observation technique. When not in prime breeding condition, or when one is not observing closely, all hatchetfish simply appear silver.
Breeding the Hatchetfish
Spawning in this species is possible but it is not common. This is a very difficult fish to breed, and it is only to be attempted by an expert breeder or someone who wants a challenge and has the time, space, and patience to attempt it.
This species scatters its eggs among the high roots of plants very near the surface of the water at the natural dusk of a tank that is lit by natural sunlight. Spawning also may occur by simulated moonlight. Temperature is very important to spawning; 86F best simulates late spring/early summer in their natural habitat.
When spawning, males do a fluttering dance parallel to the females on the shoots of finely feathered plants under the water’s surface. The sticky scattered eggs cling to these fine-leaved plants. The rearing of the fry, which hatch after 24-30 hours, is not difficult. Feed them on rotifers (infusoria) and later baby brine shrimp.
Hatchetfish are not egg eaters, so timing is not as critical as with many of the other tropical fish. However, hatchetfish parents will actively eat the fry as soon as they hatch, so remove the parents within 24 hours. Also, make sure the plants used in a breeding tank are free of snails as fish eggs are a snail's favorite food.
More Pet Fish Species and Further Research
If hatchetfish appeal to you, and you are interested in some compatible fish for your aquarium, read up on:
Check out additional fish species profiles for more information on other freshwater fish.