Instructions
Count the spikes on the fish's dorsal (top) fin. Males usually have between nine and 12 spikes on this fin, while females usually have fewer than 10 spikes. While counting the spikes on a fin isn't a definitive method, when used in conjunction with coloration and fin configuration characteristics, you can accurately determine your rope eel's sex.
Look at the overall color of your rope eel. Male coloration in rope eels tends toward an olive green, whereas the female has a light yellow-brown coloration.
Look at the caudal and anal fins of your rope eel. If the anal fin, the single fin on the bottom of the fish near their anus, is very pointed and joins the caudal fin (the tail fin) smoothly, your fish is a female. Male rope eels have a broad anal fin that's clearly separated from the caudal fin.
How to Tell the Difference Between Male and Female Rope Eels
The rope eel (Erpetoichthys calabaricus), also known as the rope fish, reed fish or snake fish, is a freshwater species found in West Africa. It prospers in aquariums of 55 gallons or larger and requires a meat diet, like bloodworms, frogs, shrimp or smaller fish, like neons. The rope eel is portrayed by some owners as an "escape artist," capable of living out of the water for several hours because of a swim bladder that functions like a rudimentary lung. Should you want to tell the difference between male and female, there are three characteristics that make the distinction.