fishsound-decenc: command not found

Have You tried accessing the binary with the full path?

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

[root@server ~]# echo $PATH

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 CentOS possible default full paths are:

/usr/bin/fishsound-decenc - from package: libfishsound-tools

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