There are many reasons for fish to die. Your fish, most likely died of old age or you were not feeding it or not feeding it enough food. It could also be a diease. If fungus was growing over the rocks, or the tank, it could be possible he/she died of that.
Black ghost knife fish are generally peaceful fish that can be kept together with other peaceful tank mates of similar size and temperament. However, they can become aggressive towards each other if there is not enough hiding spots or territory within the tank. It's best to keep just one Black ghost knife fish per tank unless the tank is large enough to accommodate multiple individuals.
Several years. It is more reliable to say that Black Ghost Knives are mature at 15-18 cm (6-7 inches) long.
The ghost knife fish uses electricity for navigating its surroundings, communicating with other fish, and detecting prey in dark or murky waters. It has specialized electric organs that help create electric fields, allowing it to sense and interact with its environment.
I'm not an "expert" on BGK but I have had one for almost 4 years now and I can say with great certainty that they are quite friendly with other larger fish. Mine lives with 2 large angelfish, a tiger barb fish a couple of bottom feeders and a plecostomus algae eater. All are healthy and happy and alive. However, I did make the mistake a while back when I purchased several guppies (cute colorful small fishes) and within a few days they had all disappeared. So yes the BGK did kill them but I think they were mistaken for lunch. Basically if the fish is small enough to be eaten by the other fish then it would be unwise to put them in the tank. The BGK has a deceptively large mouth. Also they can be aggressive when placed with other BGK or fish within that Knifefish family. In that case they should be separated in separate tanks. If the tank is big enough (has to pretty large) where the 2 knifefish's can each claim their own territory then it might not be so bad but still probably unwise. I have read that it can be done. Also, because they rely on their built in radar to find their food, having another similar fish can make it difficult for them to find the food (something about frequency being jammed or something to that effect). Makes it harder for them to locate their food.
No Only if they stab you with a knife.
black ghost knife fish gets nutrients and energy from the food it eat
No.
The maximum length of the black ghost knifefish is 40 centimetres
they can be 49cm.
No.
Yes it can
Black Ghost Knife Fish are semi-agressive. They should be fine though. The angelfish should be fine.
fish about 5in or 4in lowest
Yes if its the only one?
Depends what store!
Black ghost knife fish are generally peaceful fish that can be kept together with other peaceful tank mates of similar size and temperament. However, they can become aggressive towards each other if there is not enough hiding spots or territory within the tank. It's best to keep just one Black ghost knife fish per tank unless the tank is large enough to accommodate multiple individuals.
Your fish can not be pregnant so don't panic. They are egg layers so their eggs are fertilised and the young hatch out in the water not in the fish. Black Ghost Knife Fish (Apteronotus albifrons) grow to over 20 inches long and need a very large aquarium (at least 6ftx2ftx2ft) and are extremely hard to breed so the chances of you manageing it with your lack of knowledge (of the species) are very unlikely.