Live Rock for a Fish-Only Please Help

I just got a bran new 55g tank and I want to make it saltwater and fish only. Everytime I set into a fish store and tell them this they forcefully push me toward the live rock. I'm a student and geting all this live rock is a big expense. I have read in many books for fish only tanks live rock is unessary and that the fish will pick away all the benifical bacteria and you will be left with just rock. This same forcefullness has happened with the live sand vs. crushed coral very pushy with the live sand. DO I NEED LIVE ROOCK TO SUPPORT A SALTWATER FISH-ONLY TANK PLEASE HELP ME IF NOT WHAT SHOULD I GET? also LIVE SAND Vs. CRUSHED CORAL FOR FISH ONLY?

Thank you to those that respond.

 

Fish will not pick bacteria off of rock and eat it...I've never heard such silliness! If you don't want rock in your fish only aquarium, you don't have to have it but it will help the filtration process. Save yourself some money by buying dead base rock. It will become as populated by bacteria as live rock in no time and it costs half as much.

Products

I prefer to use sand over crushed coral but I would only buy one bag of the Carib-Sea Arag-Alive.

 

If its a F/O even fish & coral a wet dry will be what you want. And old base rock as mentioned already..

 

You might wanna buy one piece of liverock to help things along. It doesnt have to be big.

 

Congrats on the score of the new tank and welcome to 3reef!
I certainly agree with all of the advice given above...and I'd reckon that you'll soon be (despite your student's budget) itching to add a coral or 5 to the tank. Some base rock will in time (with the reefer's most important trait, patience) become live and will certainly make your fish only tank look much more realistic and give your fish a more naturalistic habitiat.
Best of luck!