tube

I am getting a 12" Piraya Piranha and want to buy some hosing or tubing of some sort to protect the cords (and Piranha) from bites to the cables. Does anyone have any links to something that could work for me?

So I have a hydor 250 canister filter and i bought a hydor inline heater to go along with it. Online it says the filters tube size is 5/8 inches on the output so i bought a inline heater for 5/8in tube. Turns out the outside diameter is 5/8 inches on the tube and the inside is about 1/2 inches...