Can Scat (Brackish) and Uaru Live Together?

Both Scat (Brackish) and Uaru are generally mild-mannered species with an aggression score of 4/10. Their matching temperaments mean neither fish is likely to dominate the other in a shared aquarium.

Scat (Brackish) and Uaru both frequent the Middle (Open Water) and Bottom (Substrate) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

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.

The safe temperature window for both species falls between 27°C and 28°C. Aim for the midpoint of this range (around 27.5°C) for optimal comfort.

The pH requirements of Scat (Brackish) (7.5–8.5) and Uaru (5–7) do not overlap, making it impossible to satisfy both species simultaneously.

Hardness requirements are incompatible: Scat (Brackish) needs 12–30 dGH while Uaru requires 1–8 dGH.

Crucially, these species require different water types — one needs freshwater while the other requires brackish conditions. This is a hard barrier to keeping them together. An aquarium test kit is recommended for monitoring.

To house Scat (Brackish) and Uaru together, plan for an aquarium of at least 540 litres with a minimum length of 150 cm. This accounts for the larger species' space requirements with an additional 20 % buffer to reduce territorial tension.

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: Sand (Sifters), Smooth Gravel (Sensitive Barbels), Established Algae (Otocinclus), Driftwood (Digestion/Hiding). Meeting these requirements will help both species thrive.

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

Feeding time deserves special attention with this pairing. Scat (Brackish) is an aggressive eater that may prevent Uaru from getting enough food.

Because Scat (Brackish) is a fast, competitive feeder, consider using sinking pellets or feeding at opposite ends of the setup to ensure Uaru receives an adequate share.