[1] The original intention of the Fish carburetor was to avoid the problems of the float chamber, and its sensitivity to sideways forces from acceleration and cornering.

In the conventional carburetor, a venturi in the airflow creates a lowered pressure and this is enough to encourage the flow of fuel through the metering jets.

[1] A second problem with the conventional carburetor was its good performance in steady conditions, but poor progression: its dynamic ability to respond, such as when suddenly opening the throttle.

This could give 'flat spots' in performance, or required great additional complexity to the carburetor such as multiple chokes, emulsion tubes and accelerator pumps.

The Fish carburetor metered its fuel flow through a calibrated tapered groove, connected directly to the accelerator pedal and the throttle butterfly.

[1] The fuel metering orifice was controlled in immediate proportion to the throttle position, in a similar manner to the motorcycle slide carburetor.

[4][5][6] The Reece-Fish is a variable choke,[citation needed] side- or downdraft design, with few moving parts to wear or adjust.