Spiny Eel Care Guide
Freshwater spiny eels (genus Macrognathus) are some of the most charismatic oddball fish you can keep: sinuous, snake-like bottom dwellers with a pointed snout, a row of tiny defensive spines along the back, and a habit of burrowing into the sand with only their head poking out. We carry the gorgeous Indian Peacock Eel (Macrognathus siamensis) and the Banded Spiny Eel (Macrognathus circumcinctus). One honest note up front: these are not true eels but specialized fish with particular needs. They are escape artists, they are scaleless and sensitive to medication, and they are nocturnal predators that will eat very small tankmates. With the right setup, though, they become surprisingly tame, even learning to take food from your hand.
Meet the Spiny Eel
Native to the rivers and floodplains of Southeast Asia, the peacock and banded spiny eels stay relatively manageable compared to their giant cousins, typically reaching 8 to 12 inches. The peacock eel earns its name from the row of eye-spots near its tail, while the banded spiny eel shows a series of vertical bars along a tan body. They are shy and primarily nocturnal, spending the day buried in soft substrate or hiding in caves and emerging at dusk to hunt. Patient keepers are rewarded as the eels grow bolder over time, recognizing their owner and venturing out during the day. This personality is what makes them a standout among bottom-dwelling oddballs.
Tank Size and Setup
Spiny eels need floor space more than height. A single peacock or banded eel does well in a 30 to 40 gallon tank with a long footprint. The single most important element is a soft, fine sand substrate, because these eels burrow and sharp gravel can scratch and infect their delicate skin. Provide plenty of hiding spots with caves, driftwood, PVC tubes, and live plants so they feel secure enough to come out. A reliable filter keeps the water clean, but the truly critical detail is the lid: spiny eels are legendary escape artists that will find any gap, so use a tight-fitting cover and seal every opening around cords and filters.
Water Parameters and Heating
Spiny eels are tropical and need warm, stable water of 75-82°F from a dependable aquarium heater. They prefer a pH between 6.5 and 7.5 and, being scaleless, they are more sensitive to poor water quality than most fish. Pristine, well-cycled water is non-negotiable: run the full nitrogen cycle before adding an eel, treat tap water with a water conditioner, and keep up with steady water changes using your maintenance supplies. A crucial caution: because they lack scales, spiny eels are very sensitive to many common medications, especially those with copper. If treatment is ever needed, use scaleless-safe fish medications at reduced doses and follow directions carefully.
Feeding Your Spiny Eel
Here is the most common reason spiny eels fail in home aquariums: they are carnivores that often refuse dry food, so do not expect them to eat flakes or pellets. They strongly prefer meaty, often live or frozen foods. Build their diet around frozen foods such as bloodworms, blackworms, brine shrimp, and chopped earthworms, offered after lights-out when they are active. Some individuals can eventually be weaned onto sinking carnivore pellets, but always confirm a new eel is actually eating, as a thin, sunken body signals trouble. Target-feeding in the evening ensures the eel gets its share before faster tankmates.
Tankmates and Temperament
Spiny eels are peaceful toward fish too large to swallow but are absolutely predators toward anything small. The golden rule: never house them with fish small enough to fit in their mouth, including shrimp, fry, and tiny nano fish, which will be eaten overnight. Good tankmates are medium-sized, peaceful, fast fish that occupy the upper water column, such as larger tetras, barbs and danios, and robust corydoras. They generally ignore other bottom-dwellers their own size, though multiple eels may squabble over the best hiding spot unless the tank is large with abundant cover. If you enjoy secretive bottom-dwellers, the kuhli loach makes a fun, eel-like companion at the smaller end, and our best bottom feeders guide has more ideas.
Health and Behavior
With clean water and a proper diet, spiny eels are hardy and can live well over a decade. Most problems trace back to three things: poor water quality affecting their scaleless skin, gravel substrate causing abrasions, and refusal to eat. Watch for a hollow belly, cloudy eyes, or skin lesions, and address water quality first. Remember their medication sensitivity if illness strikes. Behaviorally, do not panic if a new eel hides for days or weeks; this is normal as it acclimates. Dim lighting, dense cover, and evening feedings all help a shy eel settle in and eventually become the confident, hand-tame centerpiece these fish are known for.
Is a Spiny Eel Right for You?
A peacock or banded spiny eel is a fantastic fish for a patient, attentive aquarist who can provide sand, a secure lid, pristine water, and meaty foods. They are not a good fit for nano tanks, communities of tiny fish, or beginners hoping for a fish that eats flakes and is always on display. If that sounds like more than you want to take on right now, our guides on the best beginner fish and corydoras catfish point to easier bottom-dwellers. But if you are ready for a rewarding oddball with real personality, browse our available eels in the oddballs collection.
Frequently Asked Questions
Do spiny eels really need sand? Yes. They burrow, and their scaleless skin is easily scratched by gravel, which can lead to infection. A soft, fine sand substrate is strongly recommended.
What do spiny eels eat? They are carnivores that usually prefer live or frozen meaty foods like bloodworms, blackworms, and brine shrimp. Many refuse dry food, so confirm any new eel is actually eating.
Are spiny eels aggressive? Not toward fish too big to eat. They are peaceful with appropriately sized tankmates but will eat any fish, shrimp, or fry small enough to swallow, so choose companions carefully.