Kadosh and his partner were supposed to get married next month, the association said.
Shooting terror attack on Highway 4 near Ashdod kills one, wounds several others to varying degrees, including one doctor.
This arrest came just one day after the suspect’s relative, Nasir Ahmad Tawhedi, was detained in Oklahoma for allegedly planning an ISIS-inspired attack on US Election Day.
The case was cleared for publication on Thursday following a covert investigation that lasted several weeks.
Five suspects had planned a combined attack involving a car bomb and shooting, targeting a crowded area in central Israel, including the Azrieli Towers.
Rabbi Fishoff was a resident of Hadera and a father of seven.
The defense establishment is on high alert with the upcoming Tishrei holidays.
The victims of Tuesday's shooting attack included three young women - one a mother who used her body to protect her baby, according to local media. Sixteen people were wounded, police said.
The names of two other victims have not yet been released.
Seven were murdered and 17 were wounded to varying degrees, the two terrorists were shot dead by security forces.