Can Smallmouth Bass and Warmouth Live Together?

Smallmouth Bass is a semi-aggressive species (7/10), while Warmouth is semi-aggressive (8/10). This modest difference means Warmouth may occasionally assert dominance over Smallmouth Bass.

Both Smallmouth Bass and Warmouth are highly aggressive, increasing the risk of violent confrontations.

Smallmouth Bass and Warmouth 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: Two territorial species may clash over territory, especially in smaller tanks. Two aggressive species housed together increases risk of fighting.

Worth noting: Smallmouth Bass is a known jumper, so a tight-fitting lid is essential.

To improve the chances of a peaceful coexistence in this community tank: Provide a significantly larger tank (at least 50% more volume than the minimum) to allow both Smallmouth Bass and Warmouth to establish separate territories. Add plenty of line-of-sight breaks using driftwood, rocks, and dense planting to reduce territorial confrontations. 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 15°C and 25°C. Aim for the midpoint of this range (around 20.0°C) for optimal comfort.

Both fish can tolerate a pH between 6.5 and 8. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 5–20 dGH. Regular testing will ensure conditions stay within this range.

To house Smallmouth Bass and Warmouth together, plan for an aquarium of at least 680 litres with a minimum length of 180 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: Smooth Gravel (Sensitive Barbels), Driftwood (Digestion/Hiding), Plants - Densely covered, Leaf Litter/Blackwater. Meeting these requirements will help both species thrive.

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

This pairing usually fails when the tank is treated like a standard mixed community and the caution flags are ignored. Smallmouth Bass and Warmouth 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.