Can Silver Prochilodus and Threadfin Rainbowfish Live Together?

Silver Prochilodus is a generally mild-mannered species (4/10), while Threadfin Rainbowfish is peaceful (1/10). This modest difference means Silver Prochilodus may occasionally assert dominance over Threadfin Rainbowfish.

Silver Prochilodus and Threadfin Rainbowfish both frequent the Middle (Open Water) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

There is a critical concern: the Slime Coat Eater (Attacks Flat Fish) behaviour of one fish directly conflicts with the Shy / Slow Moving (Easily Stressed) trait of the other — slime coat eaters target slow-moving fish, causing severe stress and health issues..

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion.

Worth noting: Silver Prochilodus is a known jumper, so a tight-fitting lid is essential.

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 5.5 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 1–12 dGH. Regular testing will ensure conditions stay within this range.

To house Silver Prochilodus and Threadfin Rainbowfish together, plan for an aquarium of at least 450 litres with a minimum length of 150 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Providing a mix of open swimming space and sheltered areas with rocks, driftwood, or plants will keep both species comfortable and allow natural behaviour.

Specific environmental needs for this combination include: Established Algae (Otocinclus), Plants - Densely covered, Plants - Floating. Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Silver Prochilodus is a plant destroyer, which conflicts with Threadfin Rainbowfish's requirement for live plants. Compromise where possible or prioritise the more critical need.

Silver Prochilodus prefers High (River/Stream) flow while Threadfin Rainbowfish needs Low (Still Water) flow. Consider positioning filter outlets and using baffles to create zones of different current intensity within the same tank.

Silver Prochilodus and Threadfin Rainbowfish are the kind of pair that can look acceptable in a shop but become a maintenance problem at home. The main risk is not a single number in the chart; it is the way incompatible behavior, water needs, or pressure on space compounds over time once both fish are established in the same tank.