If you’re looking for an easy-to-care-for oddball for an aquarium the size of a small house (alright, not quite, but very large!), you might like to consider this week’s Fish of the Week: the black ghost knifefish (Apteronotus albifrons). This unusual species is completely black with only two white rings on its tail and a white spot on its face. Its binomial genus, Apteronotus, is derived from ancient Greek and translates to “back without wings”, highlighting a species’ peculiarity: they have no dorsal fin. Instead, these knifefish use an elongated, undulating anal fin which stretches the length of their body to move and swim in any direction: forwards, backwards, upside-down, sideways, you name it! These fish are nocturnal, coming out from their hiding places at night to hunt for insect larvae. Interestingly, another peculiarity of these fish is that it is an “electric fish”. Using electromotor and electrosensory systems, these fish produce and receive electric waves (electronic organ discharges), allowing them to detect the movements of their micro-prey and communicate with other members of the species. However, in the home aquarium environment this skill is usually solely for hunting as they are often kept singularly due to their size. Reaching a maximum size of around 50cm (20 inches), this species is not to be bought on a whim, particularly as they can live for as long as 12 or 15 years too! As well as a very large tank, these fish also require lots of dark hiding places so they can rest during the day, and a soft substrate so that their delicate anal fin is not damaged whilst hunting. However, this scale-less, South American oddball makes for a stunning focal point and can become quite tame even taking food from the hand, earning them Fish of the Week this week.
Image credit: petworlds.net - JohnC
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