fizsh: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/fizsh - from package: fizsh

You may install the required package with command apt-get install {package}

Error in other languages:
fizsh: bevel nie gevind nie
fizsh: comandă negăsită
fizsh: comando não encontrado
fizsh: commande introuvable
fizsh: command not found
fizsh: käsku ei ole
fizsh: không tìm thấy lệnh
fizsh: komanda nerasta
fizsh: Kommando nicht gefunden.
fizsh: kommandot finns inte
fizsh: komut yok
fizsh: nie znaleziono polecenia
fizsh: níor aimsíodh an t-ordú
fizsh: no se encontró la orden
fizsh: no s'ha trobat l'ordre
fizsh: opdracht niet gevonden
fizsh: parancs nem található
fizsh: perintah tidak ditemukan
fizsh: príkaz nenájdený
fizsh: příkaz nenalezen
fizsh: команда не найдена
fizsh: командата не е открита
fizsh: 命令找不到
fizsh: コマンドが見つかりません