Freshwater Rat-tail
Gymnarchus niloticus
Also known as: Aba aba, Frankfish
A five-foot electric predator that will bite the hand that feeds it.
About
The freshwater rat-tail (Gymnarchus niloticus) is one of the most extraordinary and frankly impractical fish ever to appear on a dealer's list. Found across a wide sweep of African river systems, from the Senegal and Gambia in the west, through the Niger and Chad basins, to the Nile and Lake Turkana in the east, it inhabits vegetated margins, floodplains, and swamps, and is an obligate air-breather that must have surface access at all times. It is the only member of its genus and is built unlike almost any other fish you'll encounter: no pelvic, anal, or caudal fins whatsoever, with propulsion and steering handled entirely by a long undulating dorsal fin. This gives it fluid, almost otherworldly movement in all directions. It also generates a weak electrical field running nearly the full length of its body, used for navigation and communication, and can actively shift its discharge frequency to avoid interference from other individuals nearby. Behavior-wise, this species is genuinely dangerous. Juveniles may seem manageable for a short while, but adults are ferociously territorial, completely intolerant of tankmates of any size, and will attack the keeper's hands during maintenance. This is strictly a single-specimen fish for an experienced keeper with very serious facilities. Not a casual purchase under any circumstances.
Similar species
Other fish you might consider
Good tank mates
Species that tend to coexist peacefully with Freshwater Rat-tail
From the same region
Share the same natural habitat. Great for a biotope-themed tank
Frequently asked questions
- How big does the Freshwater Rat-tail get?
- The Freshwater Rat-tail reaches about 39.5–65.5" as an adult.
- What size tank does the Freshwater Rat-tail need?
- A minimum of 2154 gallons is recommended for the Freshwater Rat-tail.
- What water parameters does the Freshwater Rat-tail need?
- The Freshwater Rat-tail does best with a temperature of 73–82°F, a pH of 6.5–8, hardness around 10–25 dGH.
- Is the Freshwater Rat-tail aggressive?
- The Freshwater Rat-tail is aggressive and is best kept alone or with robust tankmates that can hold their own.
- What does the Freshwater Rat-tail eat?
- The Freshwater Rat-tail is a carnivore. It needs a meaty, protein-rich diet of frozen or live foods.
- How long does the Freshwater Rat-tail live?
- With good care, the Freshwater Rat-tail typically lives 4-14 years.