Elephant knifefish

Care at a glance

Overview

The elephant knifefish is a nocturnal, weakly electric fish that grows to around a meter, so it needs public-aquarium space, really a tank of around 900 liters or more, and suits only keepers set up for a giant. It is peaceful and rather shy, spending the day hidden and hunting the bottom at night with a long, curved snout. Despite its calm nature it will eat fish small enough to swallow and is easily outcompeted for food by fast, greedy tankmates, so choose large, gentle companions or keep it alone. Give it a soft sand floor it cannot scrape its skin on, large caves, and dim lighting. Feed meaty foods after dark, such as earthworms, prawn, mussel, and sinking items.

In the wild

This knifefish ranges widely through the Amazon and Orinoco basins, living over the muddy and sandy floors of large rivers and channels where it probes the substrate at night. It is used to warm, soft, dimly lit water. Keep it from about 24 to 28 C at a soft, slightly acidic to neutral pH between roughly 5.5 and 7.2, kept very clean, since a big fish in enclosed water needs strong filtration and steady oxygen. A deep, soft sand bed, large smooth hiding places, and low light let it feel secure and behave naturally rather than staying buried and stressed.

Good to know

Rhamphichthys rostratus is a knifefish of the family Rhamphichthyidae, part of the South American electric knifefishes and a distant relative of the electric eel. It can reach about a meter, its body drawn into a long blade with a curved, tube-like snout used to pick prey from burrows and crevices. Rather than a strong shock like the electric eel, it produces only a weak electric field for navigating and finding food in the dark. It has not been bred in aquaria.

Did you know

Like its cousin the electric eel it generates electricity, but only a faint field it reads like radar to feel its way and locate food in muddy water, drawing prey out of the substrate with its long trumpet of a snout.

Common questions

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