What is this ninja anime from the late 70s early 80s? I have seen this anime on TV as a child, dubbed in Arabic (so I couldn't tell you what the character names are). This was during the early 80s and I don't recall much of the detail.

The protagonist is a boy, always dressed in a red kimono and long black hair tied up and armed with a katana. 

As a ninja he was able to transform to different animals (I recall a very large fish).

Wish I had more details, but it was long ago and in a language I did not understand.
I believe you are looking for the series Manga Sarutobi Sasuke, or Ninja, The Wonder Boy.

The show tells the story of Sasuke, a Koga ninja boy living in 17th century Japan, doing battle with the Iga ninja clan lead by the evil Hanzo.1



OP/ED: http://www.youtube.com/watch?v=-b7vnd8rhoY