The Fishy Turbo is another name for John Ehler's "Inverse Fisher Transform of RSI" which was detailed in the May 2004 edition of TASC magazine.
Resulting values range between 1.0 and -1.0 with bullish triggers occurring at crossovers of -0.5 and bearish triggers of 0.5.
Presentation
The chart above is a 2-minute chart of ESZ8 with the Fishy Turbo indicator added to the lower pane.