I have had my ghost for 13 months. He is 25 cm long he has grown 20 cm in the last year. I feed him frozen brine shrimp and blood worms, he goes crazy on them. He is just starting to eat from my hand, which I think is one of the best things that could happen, being such a mellow fish. I have him in with 16 Discus, which are also from the Amazon. Their water conditions are pretty much the same, although my water temp is at 29°C not 26°C, but my ghost is awesome. He comes out at day and plays with the aeration bubbles, it's really cool. I can't wait till he gets to 40 cm long.
I have set up my tank to give my ghost knife hiding places about every 15-20 cm from one side of my tank to the other. He comes out all day long, and has ever since I put him in! I think giving him lots of hiding places he can duck into in his travels makes him confident! His main "pad" is a great piece of driftwood with a hollowed out arm to it and the base is hollowed out as well, so he has two rooms to hang out in and several "Doors", so he can get home from any angle fast! He eats from my hand and has done so since day one. Got him at about 10 cm and now he is 15 cm in about 4 months. And they DO give off an electric "buzz", I learnt this one day when cleaning out the tank. But I think it is up to him to zap when he likes. GREAT GREAT fish!
We absolutely love our ghostfish which is in a 180 L tank, with two angels and six cory cats. This is a well planted tank, and he loves to hide in a "cave" he built for himself by digging out the gravel (creating three exits) from under and around a bark tree that he can get up inside of. This took him about 10 minutes and was the first thing he did when put in the tank. Loves bloodworms, comes out to eat whether plant lights are on or off, during the day. Has never bothered the other fish. Is fascinating to watch, not really having fins but a rippling motion whether he goes forward, backward, sideways, up or down. The other fish also love the bloodworms, and they all feed together. While their diet is varied, the ghost only eats the bloodworms, comes out for them. Our ghost is about 15 cm. After reading the other postings, am worried about him eating other fish, but must be I am feeding him well.
For those of you who want to know the sex of your Black Ghost Knife Fish: the males are the ones which grow to 30 cm or more and get a larger elongated head, while the females seem to stop growing at around the 25 cm mark and retain the same head shape as younger specimens. Two males DO NOT get on together but a male and some females, or females only are usually OK (although they will still have minor squabbles). Incidentally, have a look at the small white spot on the "throat" of your knife fish. That's its anus and also the spot where the gametes (eggs or sperm) emerge. All the rest is tail and electrical storage (they won't shock you - it's only to find their way around) and they can lose at least a third of their tail and grow it back again. They're great fish, I had one for 9 years (a male) which would take food from my hand and was even taught a few simple tricks. If you want to hear the electrical discharges of Black Ghosts, Brown Ghosts, Elephant Noses, Baby 'Whales', and Freshwater 'Dolphins' as 'hums', 'clicks' or 'beeps' (depending on the species) there's a circuit diagram available from the Burkes Backyard TV program.
I've spent many years retailing aquariums and studying fish, but none of them interests me more than Apteronotus albifrons; I get excited every time a new shipment of little ones arrives at our store. My first ghost knifefish was purchased over five years ago and is still going strong at almost 30 cm; I'm also currently raising a new one in another tank, he's only 5 cm and probably one of the cutest little fish! My success with the first one was attributed to his heavily planted tank, constant temperature of 27°C, soft, slightly acidic water (pH 6.8), and a good variety of food. Most people find this species will readily feed on frozen bloodworms, frozen brine shrimp, and live blackworms, but this is not a balanced diet and it can quickly contribute to polluted water or disease from unsanitary blackworms. For the first two years my knifefish ate a combination of Nutrifin sinking tablets, OSI shrimp pellets, and frozen bloodworms. He'll now eat anything including flake food, spirulina tablets, granulated food, or frozen food and spends part of the day (and night) hovering under the automatic feeder. But if you're feeding all this food you have to keep up with your water changes! One more piece of small advice on tank mates for this species: avoid putting them with Epalzeorhynchus bicolor (red tail black sharks). Hope some of this information helps someone enjoy their knifefish as much as I've enjoyed mine. Next step...try breeding them!
My black ghost knife is the crown jewel of my tank - he even outshines my brown wild caught discus. I bought him when he was four inches at a great price, and finding one at four inches is a good deal in general cause the bigger they are, the hardier. Mine loves earthworms and can sense my hand in the water. He swims out of his cave and floats around my hand, looking for food. Overall, this is a great fish... I've found it to be hardy and active, maybe since I feed it live food.