Peacock Eel
Macrognathus siamensis
Also sold as Peacock spiny eel · Spotfin spiny eel
Peacock Eel (Macrognathus siamensis) is a semi-aggressive freshwater fish that reaches about 32.5 cm (12.8 in) and swims along the bottom. It wants 75–82°F (24–28°C) and pH 6–7, can be kept singly, and needs a tank of at least 151 L (40 gal).
At a glance
| Type | Fish |
|---|---|
| Adult size | 32.5 cm (12.8 in) |
| Minimum tank | 151 L (40 gal) |
| Group size | Can be kept singly |
| Temperature | 75–82°F (24–28°C) |
| pH | 6–7 |
| Temperament | Semi-aggressive |
| Lifespan | 8–18 years |
| Eats shrimp | Yes |
Before it goes in
- Peacock Eel needs at least 151 L (40 gal). The smallest size in this library that clears that is the 40 Gallon Breeder.
- It eats small fish and shrimp — anything under about 10.8 cm (4.3 in). In this library that means Cherry Shrimp, Rummy Nose Tetra and Crystal Red Shrimp.
- It holds at 75–82°F (24–28°C). That shares a window with Betta and Cherry Shrimp, but not with Goldfish and Dojo Loach.
- It is semi-aggressive — plan the tank around it rather than adding it to a finished community.
- It jumps. An open-top tank needs a lid or a low water line.
- It digs in the substrate. A freshly planted carpet — Dwarf Hairgrass Mini and Downoi — gets lifted before it roots.
- One of them takes up roughly 62% of what a 40 Gallon Breeder will comfortably hold, so plan the rest of the stock around it.
What tank size does it need?
At least 151 L (40 gal). The smallest size here that clears it is the 40 Gallon Breeder.
Will it eat shrimp?
Yes. Shrimp are food to it, so pick one or the other.
What water does it want?
75–82°F (24–28°C), pH 6–7.
How long does it live?
8–18 years in a tank that suits it. That is how long you are signing up for.
Good tank mates
- Tank mates from this library that share its temperature window, are peaceful and eat neither it nor its young: Bristlenose Pleco, Celestial Pearl Danio, Molly, Otocinclus and Ramshorn Snail.
- Plants that hold up with it: Hygrophila corymbosa 'Siamensis', Water Sprite, Anubias nana 'Petite' and Cryptocoryne wendtii.
Often compared with
| Peacock Eel | Peacock Gudgeon | Bala Shark | |
|---|---|---|---|
| Adult size | 32.5 cm | 7.5 cm | 35 cm |
| Min tank | 151 L | 41 L | 864 L |
| Group | 1+ | 1+ | 5+ |
| Temperature | 75–82°F (24–28°C) | 72–79°F (22–26°C) | 68–82°F (20–28°C) |
| Eats shrimp | Yes | Yes | Yes |
More livestock
Sources (6) · checked Sep 2026
- Group size, Minimum tankaquariadise.com
- Group size, Minimum tankaquariumsource.com
- What it eatscichlidatlas.com
- What it eatsfishkeeper.co.uk
- fishkeepingworld.com
- fishlaboratory.com