Abstract
This study tested the ability of bluegill bullies ( Gobiomorphus hubbsi ) to detect and respond to the odour of conspecific fish upstream under neutrally odoured (rainwater) and naturally odoured (stream water) conditions. Bluegill bullies were presented with a choice of two flows of water to move into, one of which contained the odour of conspecific fish. Bluegill bullies displayed a concentration‐dependent reaction under neutral water conditions, where they were attracted to low concentrations of conspecific odour, but repelled by high concentrations of odour. This result was not consistent under naturally odoured water conditions, where no attraction towards conspecific odour occurred at low odour concentrations and only a weak avoidance of odour occurred at high concentrations. The differences revealed between natural and neutral water trials suggest the use of habitat odours over conspecific odours and cast doubt on previous studies only conducted under neutral conditions.