The tonebars define the basic sound of the guitar, just as the body wood on a traditional solid body guitar. Furthermore they are interchangeable, which allows the birdfish to alter its basic character. The tonebars are made of traditional tonewood: one pair is made of American Alder while the other is made of selected Michigan Maple. There is one fundamental aspect: because there are no body cutouts for pickups and vibrato, they aren't etiolated in their cross sectional area. Therefore the "weakest" part of the birdfish tonebars is still larger than the "weakest" cross section where the pickups and the vibrato are on a regular guitar.

By aligning the tonebars sideways from the middle of the guitar they are preloaded by the strings similar to the bridge of an acoustic guitar. They are therefore able to react very sensitively to the string vibrations. The result is the birdfish's percussive and twangy attack.

Both tonebars are bolted onto both aluminum elements with two screws each. In the tonebar there are metal thread inserts to guarantee a perfect sound transduction. They can be changed one after the other easily without releasing the strings.