Animal-World > Aquarium Tropical Fish > Freshwater Eels and Eel-like Fishes > Black Spotted Eel

Black Spotted Eel

Polka Dot Eel ~ Spotted Spiny Eel

Family: MastacembelidaeMastacembelus dayiPhoto © Animal-World: Courtesy Ken Childs

  The Black Spotted Eel may not be brightly colored but it has a beautiful design!

   The Black Spotted Eel is also known as the Polka Dot Eel or Spotted Spiny Eel. As you can see in the photo above it sports an exotic looking color pattern. Smaller specimens have fewer but larger spots. This elegant patterning makes it a beautiful fish, one that is well worth having in your aquarium.

   The Black Spotted Eel has been imported for a long time, and over the past few years many thousands have been shipped from Thailand. Mastacembelus dayi is considered to be very rare by science, but fortunately this is probably not true. Supposedly only 3 specimens have ever been found and these 3 were used to describe the species. This is probably just a case of local fisherman knowing more about the distribution of a fish than the scientists do.

   As with most members of the spiny eel family, the attractiveness of this eel lies in its unusual color pattern and interesting behavior. Although not considered to be true eels, the body shapes of all members of the spiny eel family, Mastacembelidae, are definitely eel-like.

For more Information on keeping freshwater fish see:
Guide to a Happy, Healthy Freshwater Aquarium

Distribution:    The Black Spotted Eel, called Polka Dot Eel or Spotted Spiny Eel, was described by Boulenger in 1912. They are found in Asia; western Myanmar and eastern Thailand.

Status:    The species is not listed on the IUCN Red List.

Description:    The Black Spotted Eel is elongated with a long snout. Its background coloration is a dark tan to light brown. Along the length of its body it has a series of spots in a linear fashion. The spots are relatively large, with those on the upper part being dark and those lower down becoming paler. Some of the spots, especially along the center, can often become vertically elongated rather than round. This patterning extends from the tip of its mouth to the rear of the fish. Smaller specimens have fewer but larger spots.

Size - Weight:    Fish of over 20 inches (50cm) are commonly imported. Science lists the maximum size at about 12 inches (30 cm) but since they were working with only 3 fish, this information is probably wrong.

Care and feeding:    The Black Spotted Eels are carnivores. Feeding is not a problem because they will eat most fresh or frozen foods including small fish, worms, and shrimp. They may be trained to eat freeze dried brine shrimp or bloodworms but this is not something that can be counted on. They will also eat small fishes so make sure their tank mates are too large to be able to fit into their mouths.
   They should have a tank with fine gravel or sand because they like to bury themselves. Make sure they have plenty of hiding places so they will feel secure in their new home. It is advisable to keep small specimens, those up to 6 inches, in a tank that is at least 36 inches long and about 35 gallons. Larger specimens will needing an even bigger area, tanks that are 48 inches in length or longer and 55 gallons and up will be necessary. Provide a tight fitting lid as spiny eels are escape artists. These fish respond poorly to copper based medications, so these should be avoided.

Water Region: Top, Middle, Bottom:    Black Spotted Eels with stay on the bottom of the aquarium.

Acceptable Water Conditions:    Temp: 74 - 82° F (23 – 28° C)
   Hardness: 6 - 25 dGH
   Ph: 6 - 8

Social Behaviors:    Like most spiny eels, they are not aggressive but due to their large size mouths, they may eat smaller tank mates.

Sexual Differences:    Sexual differences are unknown.

Breeding/Reproduction:    Has not been bred in captivity.

Availability:    Black Spotted Eels, also called the Polka Dot Eel or Spotted Spiny Eel, are commonly available.

Author: Ken Childs
Additional Information: Clarice Brough, CFS

Lastest Comments on Black Spotted Eel View all 13 comments on Black Spotted Eel Add Your Comment

zack - 2011-02-10 Would a black spotted eel get along with south american cichlids? Would he eat feeder guppys? Click For Replies (2) Charlie Roche - 2011-06-04 Animal World wrote in the article on the black spotted eel "The Black Spotted Eels are carnivores. Feeding is not a problem because they will eat most fresh or frozen foods including small fish, worms, and shrimp. They may be trained to eat freeze dried brine shrimp or bloodworms but this is not something that can be counted on. They will also eat small fishes so make sure their tank mates are too large to be able to fit into their mouths". The eel will grow to be about 20 inches and cichlids start out fairly small and grow to 4 - 5 inches or so. Eels also can crush their prey - my concern is the size of the cichlids and the size of the eel as the eel is not good with small fish. I would think that means guppies or neons but the crushing part bothers me a little. I think why take the chance? Spellbound - 2012-01-31 How do I know mine is eating. I had it for over 3 weeks and it seems happy and active he loves to spim all over. And I put blood worms in about ever 3 days and they dissappear. But I never actually see him eat? Reply

Rob - 2011-09-20 I've had my black spotted eel for nearly a year now and he has developed a small amount of bacteria on his tail. I clean the tank every other week to ensure a clean environment for him and he eats regularly. Any ideas on how to cure this? Thanks in advance. Click For Replies (2) Charlie Roche - 2011-09-21 Animal World article Fish Disease and Treatment lists various symptoms and the corresponding recommended treatment for all the symptoms. Try look it up and if you have any problems - just come on back and let me know. OK? bill - 2011-11-27 1st time try some salt (not your house salt) in your tank. You can find it at your fish supply store where you get your fish from. Then only use it when you change 50% of water in your tank. The more oxygen in the tank is the best way 4" round stone. I had that problem with a 12" spotted eel. It worked for me. Reply

Amy Lark-Rakow - 2011-08-30 These fish definately get larger then 12 inches. I have 2... the smaller one is just under 12 inches while the other is nearing 16 inches and both are less then 1yr old... Very similar care/personalities to M. Armatus ( Tire track ) Reply

sana - 2010-11-04 Hi! Guys, Recently I purchased blick spt eel, but it's not eating anything, plzzz tell me, what I can do? I feed him some pallets, and blood worms but no response. Click For Replies (2) Frank - 2011-08-01 Try frozen bloodworms or brine shrimp. If he wont accept it you might have to try live ones. Good Luck. jamie - 2011-08-24 Hi there, I've had my black spotted eel for about a year now & he is doing well eating mostly live tubifex worms. You might want to give that a try. Reply

Todd Monaghan - 2011-07-08 How fast do the black spotted eel, and how big are they as babies or when ready to sell? Click For Replies (1) Charlie Roche - 2011-07-09 I am not real sure I understand the question. They are very small when they are babies - but I don't think that is what you meant. It is said they have not bred in captivity. When they are imported, they are about 20 inches. Reply

Greg - 2010-04-07 I own a black spotted eel that is over 18 1/2 inches long. He doesn't feed on live bait. He likes freeze dried shrimp and only one brand. He lives in a castle and that is where he stays. I have a picture of him at about 17 inches long. I would love to show everybody what he looks like. He is a beautiful creature. Click For Replies (1) alicia - 2010-11-24 What size tank should a spotted eel live in? I am new to having pet eels we are buying it for our sister and know nothing about what they need and how to set up their aquarium. Reply

Add your comment!

View all 13 comments on Black Spotted Eel

Back to Freshwater Eels and Eel-like Fishes