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Giant Hatchetfish

Thoracocharax securis

Freshwater South America

The largest of the true freshwater hatchetfishes, boasting a deep, blade-like chest powered by enlarged pectoral muscles designed for gliding above the waterline. Strictly surface-dwelling and easily startled, they demand soft acidic water, floating plant cover, and an entirely gap-free lid to prevent fatal leaps.

Also called: Giant hatchetfish, Greater hatchetfish, Platinum hatchfish, Silver hatchfish.

6.8 cm adult length, drawn to scale. deep body.

Try it in the planner Opens a tank sized to its minimum with 6 fish added.

What it needs

ItemValueBecause
Adult length 6.8 cm Used for the Space check: the tank must be long enough for the fish to turn round.
Smallest tank 120 L, at least 90 cm long estimated The least water and floor length this species is kept in for good, as a single fish or smallest group.
Extra water per added fish 12 L estimated What each further fish adds once the minimum is met.
Waste load Class 2 of 5 estimated How much waste an adult makes against its size. Feeds the Load check.
Temperature 23 to 28 C Stock sharing a tank need overlapping ranges.
pH 5.5 to 7 Compared with tankmates in the Water check.
Hardness GH 2 to 10, KH 1 to 4 Degrees of general and carbonate hardness.
Flow Low Low-flow fish are stressed in a strong current.
Light Dim Matched to the lighting class on the needs sheet.
Group size At least 6, ideally 8 Kept alone or in small numbers it hides, fades or turns on tankmates.
Temperament Peaceful Not territorial.
Swims in Upper water Fish that use different levels share a tank more easily.
Lifespan About 5 years A fish is a long commitment.
Experience Some experience helps A guide to how forgiving the species is of mistakes.
Jumps Yes Keep the tank covered.

Tags marked estimated are judged from the size and habits of the species rather than measured, so treat them as a sensible default.

Diet and tank layout

Giant Hatchetfish is an carnivore that swims in the upper water. It is safe with plants. Give it some cover.

Tankmates

Works with

No close matches in the data. Check the pair tool.

Depends

Avoid

Compare any two fish on the compatibility page, or print the equipment for a stock on the needs sheet. How this is worked out: the method.