Hatchetfish
Carnegiella strigata
Min Tank Size
60L
Adult Size
3.8 cm
Lifespan
4 years
School Size
6+
About
Native to the slow, blackwater rivers and flooded forests of the Amazon basin, the marbled hatchetfish is one of the most visually distinctive fish you can put in a community tank. That deep, compressed body shaped like the head of an axe is not just for show. It houses enormous pectoral muscles that let these fish generate enough power to actually become airborne, skimming above the surface for short distances. No other freshwater fish does this quite like they do.
8 cm, with a silvery body marked by dark marbled streaks and a striking bronze or gold lateral stripe. The belly keel is almost comically pronounced up close.
0 pH range, low hardness, and temperatures between 23 and 28 degrees. They will not thrive in hard tap water long-term, and that catches a lot of beginners off guard.
Diet-wise, they're carnivores that naturally hunt insects falling onto the water's surface. They'll eagerly take floating foods like micro pellets, freeze-dried insects, and live or frozen fruit flies. Getting them to eat foods that sink even slightly can be tricky at first.
A heavily planted tank with floating cover like frogbit or water sprite makes them far more confident and settled. Keep them in a school of at least six and you'll see their natural behavior shine. If you've seen a community tank where something unusual is hovering just below the surface film, it was probably these.
Water Parameters
Temperature
°CpH
GH
dGHKH
dKHSwimming Level
Flow Preference
Keeping multiple Hatchetfish together
Hatchetfish are shoaling fish and need company of their own kind. Keep a group of at least 6. Smaller groups leave them stressed, washed-out in color, and prone to hiding.
Compatibility
They work well with virtually any peaceful species that stays out of the top zone. Cardinal and rummy nose tetras are a classic pairing since they share similar water parameter needs and don't compete for space. Corydoras, small plecos, and dwarf cichlids like apistogrammas can all share the tank without issue. Avoid anything large and boisterous, since hatchetfish spook easily and fast-moving tankmates at the surface stress them out. Gouramis can also be hit or miss since some individuals will pursue surface dwellers. Avoid any confirmed fin nippers like tiger barbs entirely as hatchetfish have no defense response beyond fleeing. Nano shrimp and snails are perfectly safe with them.
Commonly kept with
Species this one is most often paired withCommonly tried but avoid
Often paired, but shouldn't beCare Notes
The two things that kill hatchetfish most often are wrong water chemistry and uncovered tanks. Hard, alkaline municipal tap water is genuinely incompatible with long-term health, and a lot of fishkeepers only realize this after losing a few. An RO or remineralized water setup is often needed. The second failure mode is an uncovered tank or gaps around filter inlets and heater cords. These fish will find every gap and jump through it. Feed floating foods only, since they'll almost never chase food below the surface film, and don't skip the floating plant cover.
Behavior & Aggression
Marbled hatchetfish are genuinely peaceful and show no meaningful aggression toward tankmates or each other. Conspecific interactions are limited to loose schooling behavior with no real hierarchy or territorial disputes. They pose zero threat to fins, plants, or invertebrates. The only behavioral issue you'll encounter is stress-induced panic, not aggression. In understimulating environments or when kept in groups too small, they can become skittish to the point of repeatedly attempting to jump. More fish, more cover, less conflict with their natural behavior.
Things to Know
- A tight-fitting lid is mandatory, they can and will launch themselves out of the tank.
- Sensitive to poor water quality, do not add to immature tanks.
- Rarely survive in hard alkaline water, soft acidic conditions are essential.
- Skittish, loud sounds or sudden movements can trigger panic jumps.
- Floating plants help them feel secure and reduce jumping behavior.
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