Half-ocellated spiny eel
Macrognathus semiocellatus
Also known as Semiocellatus spiny eel, Semi spotted eel
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
- Tankmates with caution
- Swim level
- Bottom
- Difficulty
- Medium
- Breeding
- No record
- Rarity
- Rare
- Origin
- Chao Phraya and Mekong basins
- Family
- Mastacembelidae
Overview
House the half-ocellated spiny eel alone, since it is solitary and squabbles with its own kind in a shared tank. It is a small sand-burrower that lies hidden through the day and works the bottom at night, so a soft sand bed deep enough to vanish into is the first requirement. It is peaceful toward tankmates it cannot swallow but will eat very small fish, so keep companions calm and modestly sized. Feed meaty foods such as frozen bloodworm, blackworm, tubifex, and finely chopped earthworm, offered near the floor after dark. Around 200 liters, floored with fine sand and closed with a snug lid, keeps it well.
In the wild
The half-ocellated spiny eel lives in the Chao Phraya and Mekong basins of Thailand, where it buries in silt, sand, and fine gravel along slow, vegetated stretches. Recreate that with a soft sand base, planted or wood cover, and gentle flow. Hold the temperature in the 23 to 28 C band and the pH from about 6.0 to 7.5, soft to neutral, with clean, stable water and enough fine substrate for it to bury completely.
Good to know
Macrognathus semiocellatus is a small spiny eel of the family Mastacembelidae, reaching about 23 centimeters. Tyson Roberts described it in 1986. The name means half-ocellated: a row of dark marks sits along the base of the soft dorsal fin, some fused with bars on the body, so the eyespots look only half formed. No captive breeding has been recorded.
Did you know
Roberts named the fish semiocellatus, half-eyed, because its dorsal spots never close into complete eyespots the way related species do; they read as rings and bars left partly finished.
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 do Half-ocellated spiny eel need?
Half-ocellated spiny eel are comfortable at 73–82°F (23–28°C) with a pH of 6.0–7.5.
How big do Half-ocellated spiny eel get?
An adult Half-ocellated spiny eel reaches about 9.1 in (23 cm).
Where to buy
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Related species
Burmese spiny eel
Macrognathus orthosemosFreshwater8.7 in (22 cm)53 gal (200 L)73–82°F (23–28°C)Line-spot spiny eel
Macrognathus lineatomaculatusFreshwater8.7 in (22 cm)53 gal (200 L)73–82°F (23–28°C)
Mae Klong spiny eel
Macrognathus meklongensisFreshwater9.8 in (25 cm)70 gal (265 L)73–82°F (23–28°C)
Tapir spiny eel
Macrognathus tapirusFreshwater8.3 in (21 cm)53 gal (200 L)73–82°F (23–28°C)
Half-banded spiny eel
Macrognathus circumcinctusFreshwater7.9 in (20 cm)57 gal (215 L)75–81°F (24–27°C)
Pavo spiny eel
Macrognathus pavoFreshwater7.5 in (19 cm)53 gal (200 L)73–82°F (23–28°C)