April 6

Fire Eel Fish – Appearance, Care, Feeding, and Breeding Information


Fire Eel Fish

Fire Eel they are generally peaceful; the fish can prove challenging for aquarists to keep, and this is due to their size. Owing to this, there is a need for a big tank. The fish also love to burrow a lot.


50 cm


55-180 gallons








    20 years

    Fire eel are a dark brown bottom-dwelling fish species with the appearance of an eel. They are widely distributed in south-Eastern Asian waters where they can grow up to a length of 32 inches.

    Well, it is worth noting that the ‘fire‘ in their name is not just another addition. They are capable of releasing spines when threatened, you should not be deceived by their peaceful nature. Again, that they are good at escaping should keep you on your toes when tending for one.

    The characteristics, behaviour and feeding habit are discussed in detail in this article. Furthermore, you will get to read about how to breed and keep them in the home aquarium.


    The Fire Eel Fish (Mastacembeius erythrotaenia) belongs to the species of spiny eel and it is the largest in this species.  Its origin can be traced to Southeast Asia; however, it is commonly found all over the world, because it is actively involved in the field of aquarium trading.  The countries where fire eel fishes are found in plenty are Vietnam, Indonesia, Pakistan, Cambodia, Burma, and Laos.

    It is an omnivorous fish that feeds on invertebrates like larvae & worms, plant matter, small fishes and dead organic matter.  They are mostly found on river beds with slow-moving waters and the flood plains. They love staying in the muddy bottom of the water with only their snout sticking out at times.

    Physical appearance

    The fire eel fishes don’t resemble an eel, but it is quite elongated and big, which has given enough reason for this fish to be named this way. They grow to be quite long and they can reach up to 3’3” in length when they are in the wild. In captivity, though, they can grow to a maximum length of about 20 inches. The fire eel fish is known for its distinct pointed snout and underslung mouth.

    The compressed body of the fish is quite flat at the tail portion. This is the place where the body joins the caudal fin. It comes in colors or dark brown or grey. The stomach region is also of the same color, but in a lighter shade than the original. You will find that the fire eel fish has differently-shaped red stripes and dots all over its body. These patterns are unique to the individual fishes, as they depend on various factors.

    The age of the fish, the region where it is grown and the tank condition where it is put up decide the type of stripes or dots on its body. Younger fishes have yellow or amber patterns of stripes or dots; these colors change to dark red when the fish get older. You may notice a deep red shade in the anal, pectoral and dorsal areas of these fire eel fishes.

    The protruding eyes, extended nostrils, two divisions of dorsal fins and narrow, long dorsal & anal fins make the fire eel fish quite different from other fishes. Till today, the fire eel fishes form an essential part of the diet of the locals of Southeast Asian countries.

    Caring for the fire eel fish

    Today, these fishes are in great demand by lovers of aquarium pets, because of their unique look. If you are considering bringing home a fire eel fish as a pet, you have to exercise a great deal of caution. These are not like other aquarium pets as they demand a distinct tank setup to feel comfortable. In this section, we will give you an idea on some of the points that need to be on your checklist when you want to buy the fire eel fish as a pet.

    Tank prerequisites

    You should remember that fire eel fishes grow very rapidly. Therefore, you have to choose tanks that can accommodate their size.

    You should choose a tank that can hold at least 350 liters of water for this purpose. You will need at least a 55-gallon tank for juveniles and at least a 180-gallon tank for the adults. Since these fishes love to stay in muddy bottoms, you should then fill up your tank with a mud substrate layer.  This layer should be around 5 cm thick so that the fire eel fish can safely settle down there comfortably.

    You should add rocks in the tanks so that the fishes can hide there when they don’t have to come up in the water. You need to ensure that the temperature is always maintained at about 74 to 82 degrees F. The quality of water is an important factor that decides the health of the fish staying in it. Hence you need to ensure that you clean the water regularly with a highly effective filter. You have to keep the water flowing at all times so that the fire eel fish feels comfortable inside.  You also need to check the pH balance of your water to see if it is at the optimum level between 6.8 and 7.5.

    Cover the tank properly so that you don’t give any room for the fish to escape. Remember, these are very aggressive fishes that don’t miss the smallest chance to get out of captivity.  You also need to ensure that the water hardness level is maintained at 15 always and that the tank has enough air circulation.


    The diet of fire eel fishes can include live, dead and frozen foods. Insect larvae, small fishes, crabs, worms, snails, bloodworms,tilapia, shrimps and tubifex are some of the common foods that you should include in the diet of the fire eel fishes.

    Are there any diet restrictions that you need to follow?  What is the quantity and frequency of feeding schedule that you need to follow while taking care of fire eel fishes? Read on to know more about them.

    Young and adult fire eels love to eat out of your hands. They will recognize their owners’ faces very easily; therefore, they will be quite eager to eat when they are ready. More often than not, young fire eels are quite content with some bloodworms. Adult fire eels need a balanced diet that consists of shrimps, fishes, insects and earthworms. They are really big fishes and they need more than just ordinary fish food to keep them content, healthy and happy.

    Some tips that will help you

    Don’t be surprised when you notice your fire eels not eating common foods such as bloodworms or night crawlers when you put them out in the bowl during the first few days. These fishes are quite shy and they take time to get adjusted to a new setup. Leave the bowl in the tank and let your fish eat them whenever it feels hungry. Sometimes, it searches for food during the night when you are not around.

    When you feed live insects to fire eels, it is highly recommended that you observe them closely to watch for allergies, if any. Some fire eels may fall sick when you feed them live insects. While feeding frozen fishes or insects, it is better to cut them into small pieces first, so that it is easy for the fire eels to eat them.

    You should avoid feeding commercial pellets to your fire eel fish as they can make the fishes fall sick soon. When your fishes have grown into adults, you shouldn’t feed them small and ordinary fishes, as they won’t be enough to provide the necessary stamina for the adult fishes.

    What to do if your fire eel is not eating at all?

    Fire eel fishes are nocturnal fishes that come during the night to eat the food that you have kept in the bowl.  They normally hide under the rocks as they take some time to get adjusted to the new surroundings. While this is natural, you should watch out for extreme cases where the fire eels don’t come out at all from their hiding spots. They can go without food for a few days, but if they don’t come out of their hiding spot for more than a week, it could be because of one of these reasons:

    • The quality of the water tank is not good, which leads to a negative impact on the fire eel’s appetite.
    • The water’s hardness, pH balance and other chemicals need to be tested regularly so that it doesn’t cause any disturbance to the fire eel while coming out of the hiding spot.
    • The tank and the hiding spot are not comfortable or spacious enough for the fish to come out of, which is why it chooses to stay indoors.
    • You have kept the wrong foods like flakes inside the aquarium, which can pollute the water and cause health hazards in the fire eels.

    In short, you have to watch out for the signs that your fire eels give out while you feed them certain foods. As long as they are happy and active, you can continue with the foods that you are giving right now.


    Here is a disclaimer – when in captivity, it is quite a difficult challenge to carrying out breeding between the male and female fire eels. The female fire eels are bigger than the males. Their bodies have subtle colors whereas their male counterparts have very brightly-colored bodies.  Breeding fire eel fishes involve the use of hormonal injections; however, the truth is that, even with these injections, the results are not quite satisfactory.

    Opt for breeding in captivity, only if you are ready to take up the challenges, time and effort associated with the process. Here are the steps to follow:

    • First, you need to get the tank settings right. This involves temperate, light and water settings. The tank water’s hardness should be of 10 and its pH balance should be maintained between 7 and 7. 2. You will need at least a 90-gallon tank for this purpose. The water temperature should be around 29 degrees Celsius.  You have to fix four sprayers in the four corners of the tank to provide enough aeration. Ensure that you have also fixed highly effective water filters so that the water quality is maintained at optimum levels always. You have to ensure that you have proper feeds such as insect larvae, bloodworms and the like.
    • The male and female fire eels are put inside the tank together. Immediately, the male fish hunts down the female and squeezes the eggs out from her body. During one session of breeding, a female fire eel fish lays about 670 to 1000 eggs! The fishes are then taken out of the tank after this spawning process.
    • The eggs remain in the tank while you renew the water supply and make it as fresh as possible to create the perfect ambiance for the eggs to hatch. It is highly recommended that you change the lights to dim at this stage.
    • Within a few days, you will notice that the eggs start to hatch, with the help of methyl blue. During the first few days, the yolk sac is the food of the fry.
    • They are then introduced to ground brine shrimp gradually. You will notice that the fry grows very quickly and when given healthy foods like these, don’t be surprised to see their size growing phenomenally.

    If you decide to breed fire eels, you should take the help of a specialist because it is a long and complicated process that can go wrong, if you don’t take the necessary precautions.


    Do fire eels make for good pets? If this is the question running in your mind, here is the answer – yes, if they are left alone and if you invest 100% time and effort in maintaining it.  When they are left in the tank by themselves, they are very peaceful fishes and go about hiding in the rocks, coming out only to eat the foods that you give them. However, when they are put up with tank mates they are not comfortable with, they turn quite aggressive and may make their mates their prey!

    While they are in the tanks, their favorite pass-time is to dig burrows in the muddy bottoms that they love to stay. Therefore, it is not advisable to keep plants with roots in the same tanks as these fire eels. It takes only minutes for the eels to uproot them.  Floating plants are always a good option, instead.  They love to be hand-fed by their owners and they don’t mind coming out of their hiding spots during the day to feed, if the aquarium lights are dim and comfortable. They are known as omnivores, but they feed on plants and vegetables only very rarely. They always prepare live and frozen worms or insects.

    Common diseases

    Like most of the spiny eel fishes, fire eels are quite prone to bacterial infections. They are very particular about the quality of water and substrate that they live in. Once they fall sick, it becomes quite tough to treat them; therefore, it is very important that you do whatever it takes to keep the tanks safe and hygienic to prevent your fire eels from falling sick.

    If the substrate that you use isn’t soft enough, that can cause infections in fire eels.  These fishes are quite fussy in nature. Hence, you have to get one home only if you think you can give your best in maintaining and taking care of it.

    Aquarium Mates

    Fire eels do not get along with all fishes. Therefore, you have to choose their aquarium mates very carefully. When you keep small fishes or shrimps in the same tank as the fire eels, you shouldn’t be surprised to see the eels eating up their tiny counterparts.  Huge fishes such as the Green Terror, Angel Fish and Oscar Fish are good aquarium mates for the fire eels.

    You should never keep two fire eels together in the same tank as they start fighting with one another. They want to take control of the territory where they stay; therefore, they don’t like to share it with another of their same kind. Large, yet calm fishes, like the ones that we mentioned above, are good options to be kept along with the fire eels.


    Maintaining a fire eel fish is quite a complex task, because of its sheer size. The juveniles grow very quickly and before you realize you might need a tank that is almost double the size of the tank that you currently own. Therefore, it is highly recommended that you first list down the requisites for caring for a fire eel and go for it only if you think you can do justice to this large spine eel.

    You could also join online forums of fellow fire-eel owners to get first-hand information from them about the challenges they face while maintaining their large fire eels. This will give you an idea to assess if you have the energy and resources to take care of it. Remember, these pets do take a long time to open up to you, but once they do, you will realize that it was worth the wait!

    Unlike most of the other aquarium pets, the fire eels are very particular and choosy about their tank and water settings. Always ensure that you use the right quality of water in the tank to prevent your fire eels from falling sick. Good luck with your fire eels!


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