Gasteropelecus sternicla
| Difficulty | Medium-High |
| Minimum Tank Size | 20 Gallons |
| Diet | Carnivore |
| Water Parameters | 73-78 F, pH 6-7 |
| Aggression | Peaceful |
| Size | 2.5" |
Hatchet Fish are probably my favorite freshwater fish out there, especially the silver hatchet. They have a unique body shape with a nice bright body that easily stands out even to people who have not owned an aquarium. Usually to do this you need much larger, more demanding fish like oscars, eels or puffer fish. Yet the small body silver hatchet can draw the same attention, even more so when put in a school of eight or more. They enjoy moderate waterflow, so a powerhead in the tank is certainly something to consider.
The Silver Hatchet can live for over five years, with the average being around four years. They will live longer when placed in a school of hatchets, as this will reduce the stress they feel while in the tank.
Silver Hatchets do well in groups but can be kept with just three if you need to be conservative with your water space. It is very important that you do not overcrowd tanks with silver hatchets for a number of reasons. The Silver Hatchet is odd in that it is hardy and rarely gets sick when kept in good water conditions. However when water parameters shift they are quick to get sick. Think of them as a low stress tolerance fish. Too hot, too cold water as well as shifting pH can bring Ich to the hatchets, which can then spread in the tank. To combat any health issues, the Silver Hatchet’s tank should have watcher changes twice a week. This is fairly frequent compared to other fish, which is part of why their care level is so high.
Behavior & Aggression
Let’s continue the discussion of why the Silver Hatchet should not be kept in an over crowded tank. They are very peaceful fish. This is in part due to the difficulty in breeding them in the home aquarium. This means males will not often compete with each other, making their aggression even lower than most peaceful fish.
As they are such a peaceful fish they are very easily startled by other fish or movement outside of the aquarium. They will jump when scared, and their thin bodies make this a big problem in two different ways. First off they can easily get out of the tank through very small gaps. I recommend covering any holes made for filters, heaters and wires with a mesh net or towels.
The second issue is the distance they can jump despite their small bodies. This is really well seen in the video linked below.
While this poses no issue in the wild, our tanks will have hard covers just above the waters surface. The hatchet fish will jump right into the lid and hurt themselves. If the tank is over crowded they will be even more on edge and likely to jump.
Diet & Feeding
The Silver Hatchet has evolved to eat foods off of the surface of the water. As they have such thin stomachs they require at least two feedings a day to maintain a healthy diet. They enjoy standard prepared food such as flakes and floating pellets as well as frozen foods. Any food that will stay at the surface will at least be picked at by the hatchet. That being said they are very bad at eating food that has already sunken into the tank. Because of this they make excellent tank mates with bottom feeders such as cory catfish.
Breeding & Sex Differences
The Silver Hatchet has not been bred in captivity successfully.
The only notable difference between males and females is their width. The females will be slightly wider than the males. Their markings and fins are identical.
