Question

Why were anode rays also called as canal rays

Answer 1

Because they were produced by the holes or channels in the Cathode.

Answer 2

These rays are beams of particles moving in a direction opposite to the "cathode rays," which are streams of electrons which move toward theanode. Goldstein called these positiverays Kanalstrahlen, "channel rays" or "canal rays", because they were produced by the holes or channels in the cathode.