Can Peacock Eel and Threadfin Rainbowfish Live Together?

Peacock Eel is a peaceful species (2/10), while Threadfin Rainbowfish is peaceful (1/10). This modest difference means Peacock Eel may occasionally assert dominance over Threadfin Rainbowfish.

In terms of spatial distribution, Peacock Eel prefers the Bottom (Substrate) zone, whereas Threadfin Rainbowfish occupies the Top (Surface) and Middle (Open Water) zones. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion. Aggressive eaters may outcompete shy fish for food, leading to malnutrition. Aggressive eaters may outcompete shy fish for food, leading to malnutrition. Shrimp eaters may also prey on very small nano fish.

Worth noting: Peacock Eel is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Peacock Eel is a known jumper, so a tight-fitting lid is essential.

To improve the chances of a peaceful coexistence in this community tank: A larger aquarium with ample hiding spots can help diffuse aggression and give the less dominant fish space to retreat.

The safe temperature window for both species falls between 23°C and 28°C. Aim for the midpoint of this range (around 25.5°C) for optimal comfort.

Both fish can tolerate a pH between 6.5 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 5–12 dGH. Regular testing will ensure conditions stay within this range.

To house Peacock Eel and Threadfin Rainbowfish together, plan for an aquarium of at least 150 litres with a minimum length of 90 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Because this pairing requires extra vigilance, include plenty of hiding spots — caves, driftwood, and dense plant clusters — so the less dominant fish can retreat when needed.

Specific environmental needs for this combination include: Sand (Sifters), Smooth Gravel (Sensitive Barbels), Plants - Densely covered, Plants - Floating. Meeting these requirements will help both species thrive.

Both species do well with low (still water) water movement, so a standard filtration setup rated for the tank volume should suffice.

This pairing usually fails when the tank is treated like a standard mixed community and the caution flags are ignored. Peacock Eel and Threadfin Rainbowfish need extra room, more cover, and closer observation during the first few weeks so small aggression, feeding, or territory issues do not snowball into a long-term problem.

Feeding time deserves special attention with this pairing. Peacock Eel is a known shrimp eater and may prey on small invertebrates or nano fish like Threadfin Rainbowfish. Peacock Eel is an aggressive eater that may prevent Threadfin Rainbowfish from getting enough food. Threadfin Rainbowfish is an aggressive eater that may prevent Peacock Eel from getting enough food.

Because Peacock Eel is a fast, competitive feeder, consider using sinking pellets or feeding at opposite ends of the setup to ensure Threadfin Rainbowfish receives an adequate share.