You can, the electrical stuff is either grey or orange and made of PVC - I would not use it for structural stuff like hanging a light fitting over a tank.
You can get steel or rigid conduit, but I don't think it has the flanges that you see in the pic, and you usually have to thread it and use joiners (you could ask Simian, it has been a long time since I have had to deal with conduit) or maybe that is water pipe?
The pointy stick was a gift from a HBAS and NZKA member...