Rope Fish
Erpetoichthys calabaricus
Min Tank Size
180L
Adult Size
40 cm
Lifespan
15 years
About
Native to the slow-moving rivers and swamps of West and Central Africa, the rope fish looks less like a fish and more like something that slithered out of prehistoric times. That long, serpentine body covered in interlocking armor-like scales, a pair of tiny useless-looking pectoral fins, and a pointed snout make it one of the most distinctive animals in the hobby. Adults reach around 38 centimeters, which surprises a lot of people who bought a juvenile half that size. They're members of the Polypteridae family, which means they're ancient, air-breathing, and built to survive in oxygen-poor environments. This also means they need unobstructed access to the surface at all times.
Water quality doesn't need to be extreme in any direction. A pH between 6.0 and 7.8, temperatures around 24 to 26 degrees Celsius, and soft to moderately hard water all work fine. They tolerate a range of conditions better than many oddball species, which is part of what makes them approachable despite the intermediate difficulty rating.
What gets beginners in trouble isn't the water chemistry, it's the escape factor and the feeding. Rope fish are relentless about finding gaps. A lid that looks sealed often isn't sealed enough for them.
Feeding is carnivore-only: earthworms, bloodworms, small pieces of shrimp, and similar meaty foods. Dry foods are rarely accepted, especially at first. They hunt mostly by smell rather than sight, which matters when placing food.
A relaxed, slow-moving fish during the day, they come alive at night. Keeping more than one is usually fine as long as there's enough space and cover.
Water Parameters
Temperature
°CpH
GH
dGHKH
dKHSwimming Level
Flow Preference
Keeping multiple Rope Fish together
Rope Fish is mildly territorial. Small groups can work in spacious tanks with broken sightlines, but expect occasional squabbles.
Compatibility
Good tankmates need to be definitively too large to eat, which generally means fish in the 10 centimeter range or bigger. Larger cichlids, robust barbs, medium to large gouramis, and similarly sized catfish all work well. In a big enough tank, bichirs are a classic and logical pairing given shared ancestry and similar needs. Avoid anything small and slim, as rope fish seem to target elongated shapes in particular. Shrimp and snails will be eaten consistently. Fish with very long, flowing fins aren't at risk of nipping from the rope fish itself, but the same tank conditions that suit rope fish often attract other species that are nippers.
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 rope fish in captivity are escapes and starvation. A single gap around a filter inlet, a heater cord, or a loose-fitting lid section is enough for them to squeeze through and end up on the floor. Foam baffles and tape are common fixes. On the feeding side, they need meaty foods delivered at night or just after lights-out, when they're actively hunting. Dropping food in during the day and assuming they'll eat it usually doesn't work. They can go off food during acclimation for weeks, which panics new owners. Patience and nighttime feeding usually resolve it.
Behavior & Aggression
Rope fish aren't aggressive in the typical sense. They don't chase, intimidate, or nip. What they do is eat things. Any fish or invertebrate small enough to be considered prey will eventually disappear, usually overnight. They have surprisingly large mouths for their slender profile, so the size threshold for what counts as a meal is bigger than most people expect. Toward fish of similar or larger size they're completely indifferent. Multiple rope fish kept together tend to pile into the same hiding spot and coexist peacefully, though competition for space can cause mild jostling.
Things to Know
- Extreme escape artist, every gap in the lid must be sealed completely
- Will eat any tankmate small enough to fit in its mouth
- Can breathe air, but must always have access to the surface
- Groups are fine but all hiding spots must be sized for individual use
- Nocturnal feeder, daytime feeding is often ignored or refused
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