The marbled hatchetfish (Carnegiella strigata) is a lovely little fish that is not that common in the aquarium hobby. Once you see this gem — or any other hatchetfish for that matter — you will never forget the fish. They are sometimes confused with C. marthae, a similar fish that goes by the common name of blackwing hatchetfish.
Marbled hatchetfish typically reach only 1 to 1.5 inches in length, and they are extremely laterally compressed fish. The reason for the common name is obvious the first time you ever see one from the side — its body really does look like a little hatchet. The tail is the handle, and the body is the blade. The basic body color of the marbled hatchetfish is burnished silver with random black stripes or blotches over the entire body. Marbled hatchetfish fins are clear, and the pectoral fins are long and curved. These fins allow the marbled hatchetfish to soar out of the water. Marbled hatchetfish are accomplished jumpers that should always be kept in an aquarium with a complete cover.
Marbled hatchetfish are in the characin family, which encompasses a large number of fish, including the tetras. Marbled hatchetfish are native to South America, occurring throughout the Amazon and Orinoco river basins. When I import them for my fish wholesale business, they most often come from Guyana, though they are available from many places. Virtually all of the marbled hatchetfish that come into our hobby come from the wild, and I do not know of any place where marbled hatchetfish are bred commercially.
Keeping Marbled Hatchetfish
Since all of the marbled hatchetfish in the hobby come from the wild, they can at times be difficult to keep in an aquarium. My experience is that marbled hatchetfish are much more difficult to keep than the silver or common hatchetfish (Gasteropelecus sternicla), which is a larger species. All hatchetfishes do best in aquariums with soft, acidic water.
Marbled hatchetfish are very peaceful and do much better if kept in schools of six or more. A single marbled hatchetfish (or even two) will not do as well as it would in a larger group. Marbled hatchetfish can be kept with any other small fish that prefer soft, acidic water conditions, including cardinal tetras, phantom tetras or any of the smaller rasboras. For their temperature range, marbled hatchetfish tend to be happier on the warm side, anywhere from the high 70s to low 80s Fahrenheit.
To show marbled hatchetfish at their best, keep them in a densely planted aquarium with excellent water quality and a fairly strong water flow. Filter their aquarium with an outside power filter or a canister filter. If you float some canopy plants, such as water sprite, on top of the water surface, you’ll find that marbled hatchetfish will be very “happy” hanging out under the floating aquatic plants.
In addition to cautioning hobbyists that marbled hatchetfish are accomplished jumpers and require a completely covered aquarium, I would also suggest that you be selective in purchasing these fish. Since marbled hatchetfish are all wild-caught, your local fish store will only have them at certain times of the year. Marbled hatchetfish are notoriously bad shippers, so make sure that your local fish store has had the batch of marbled hatchetfish for a week or more. In addition, request to watch them eat. If they are eating, they are probably ready to be moved again.
Some key factors in keeping marbled hatchetfish are:
- Well-filtered water with a fair amount of movement
- Water temperatures in the high 70s, low 80s
- Make sure all foods float — they only eat from the water surface.
Marbled hatchetfish can at times be difficult to get started eating fish foods because they all come from the wild and have been subjected to the rigors of shipping. Marbled hatchetfish eat a wide variety of small insects and larvae in the wild, and sometimes they will not feed when first introduced into a tank. While marbled hatchetfish are small fish, their mouths are much larger than you may expect. They eat with a “jumping” motion, and when acclimated they attack any morsel that may be floating on the water. Marbled hatchetfish will only take food that is floating on the water surface, so it is important to make sure they are taking food and that any food that sinks will be eaten by other fish in the aquarium.
I have had excellent results feeding my marbled hatchetfish freeze-dried Mysis shrimp. Once the fish have begun feeding, they will take a wide variety of floating dry or freeze-dried foods.
Once marbled hatchetfish have acclimated to the conditions of an aquarium and are eating well, marbled hatchetfish make excellent citizens in a community of small fish that like warm water on the soft, acidic side. There are reports of marbled hatchetfish breeding in captivity, but I do not know anyone who has successfully spawned them, let alone raised babies. Presumably, they are egg-scatterers like other characins, and they provide no parental care to the eggs or babies. They are a very interesting fish with a unique body shape — just make sure to keep the aquarium completely covered.