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Half-ocellated spiny eel

Macrognathus semiocellatus

Also known as Semiocellatus spiny eel, Semi spotted eel

FreshwaterFish

Half-ocellated spiny eel (Macrognathus semiocellatus)

Care at a glance

Temperature
73–82°F
23–28°C
pH
6.0–7.5
Adult size
9.1 in
23 cm
Minimum tank
53 gal
200 L
Temperament
Mostly peaceful
Social behavior
Solitary
Tankmates
With caution
Swim level
Bottom
Diet
Carnivore
Difficulty
Medium
Breeding
No record
Rarity
Rare
Family
Mastacembelidae
Origin
Chao Phraya and Mekong basins

Overview

The half-ocellated spiny eel is a small sand-burrower for a calm, soft-bottomed tank. It is best kept by someone past the beginner stage.

Did you know

The half-ocellated spiny eel's name, semiocellatus, means half-eyed. A row of dark marks runs along the base of its soft dorsal fin, some fused with bars on the body. Unlike the spots of related species, they never close into complete eyespots, and read as rings and bars left partly finished.

Caring for the half-ocellated spiny eel

Give the half-ocellated spiny eel at least 53 gal (200 L), floored with fine sand and closed with a snug lid. It lies hidden through the day and works the bottom at night. A soft sand bed deep enough to vanish into comes first, with planted or wood cover and gentle flow.

Keep the water soft to neutral, at 73 to 82°F (23 to 28°C) and a pH of 6.0 to 7.5. It needs clean, stable water. Feed meaty foods such as frozen bloodworm, blackworm, tubifex and finely chopped earthworm, offered near the floor after dark.

House it alone, since it is solitary and squabbles with its own kind in a shared tank. It is peaceful toward tank mates it cannot swallow but will eat very small fish, so keep companions calm and modestly sized. No captive breeding has been recorded.

Good to know

The half-ocellated spiny eel, Macrognathus semiocellatus, is a small spiny eel of the family Mastacembelidae. Tyson Roberts described it in 1986. It is also called the semiocellatus spiny eel or semi spotted eel.

In the wild

The half-ocellated spiny eel lives in the Chao Phraya and Mekong basins of Thailand. It buries in silt, sand and fine gravel along slow, vegetated stretches.

Common questions

What size tank does a half-ocellated spiny eel need?

A half-ocellated spiny eel needs at least 53 gal (200 L). It spends most of its time in the bottom.

What temperature and pH does a half-ocellated spiny eel need?

A half-ocellated spiny eel is comfortable at 73–82°F (23–28°C) with a pH of 6.0–7.5.

What does a half-ocellated spiny eel eat?

A half-ocellated spiny eel eats meaty foods such as frozen bloodworm, blackworm, tubifex and finely chopped earthworm. Offer them near the floor after dark.

How big does a half-ocellated spiny eel get?

An adult half-ocellated spiny eel reaches about 9.1 in (23 cm).

Related species