Marbled Hatchetfish Care: Tank Setup, Feeding & Schooling
The Marble Hatchetfish (Carnegiella strigata) is an unusual and eye-catching surface dweller with a deep, keel-shaped body and intricate marbled patterning. Named for its hatchet-like profile, this peaceful nano fish spends its time near the top of the tank, adding activity to a layer many aquariums leave empty. This marbled hatchetfish care guide covers how to keep these small freshwater fish safe and thriving, from surface feeding to stable water conditions.
Quick care overview
- Adult size: about 1.5 inches (3.5–4 cm)
- Minimum tank size: 15–20 gallons
- Temperature: 75–82°F
- pH: 5.5–7.0
- Temperament: peaceful, schooling
- Diet: omnivore (surface feeder)
- Lifespan: 3–5 years
A tight lid is essential
The single most important thing to know about hatchetfish is that they are exceptional jumpers. In the wild they leap out of the water to catch insects and escape predators, and in the aquarium they will jump through any gap. A tight-fitting lid is essential for a tightly covered tank: use a snug lid with every opening around equipment and cables closed, because even a small gap can lead to a lost fish. Keep floating plants arranged so fish still have access to the water’s surface and open swimming room. Keep the water level a little below the rim to give them a landing buffer.
Tank setup
Hatchetfish appreciate a well-planted tank with floating plants, which diffuse light, provide security, and mimic their shaded natural habitat. They prefer soft water that is slightly acidic, with stable temperature, good oxygenation, and gentle flow rather than a powerful current. In a freshwater tank, floating plants and other surface cover can reduce stress without blocking the entire surface. Open surface swimming space is important since that is where they live. Browse live aquarium plants, including floating varieties, for their setup. As with most soft-water fish, they do best in a mature, stable tank—keep parameters steady with our water change guide.
Diet and feeding
As surface feeders, hatchetfish do best with floating foods that remain accessible at the top of the aquarium. Offer floating flakes and small pellets, and supplement with surface-taken live and frozen foods such as fruit flies, small insects, daphnia, and bloodworms. They may ignore food that sinks quickly, so feed small amounts they can catch at the top.
Behavior and schooling
Marbled hatchetfish are social, shoaling fish and feel secure in groups of at least six; a larger group is beneficial when tank dimensions and filtration allow. Kept alone or in pairs they become stressed and shy; in a group they are calmer and more active. They spend nearly all their time in the upper third of the tank.
Tank mates
Their peaceful, surface-oriented lifestyle makes them great companions for fish that occupy other levels of the tank. Good choices include small tetras and rasboras, corydoras, and peaceful dwarf cichlids. Avoid large or aggressive fish and anything that might nip. For general schooling-fish tips, see our care basics for schooling fish.
Is the marble hatchetfish right for you?
If you have a securely covered, planted tank and want a distinctive fish to bring the surface to life, the marble hatchetfish is a rewarding and peaceful choice. Just remember the lid. Find them among our freshwater fish.