Hey I am looking to set up a fish only tank with live rock it is going to be a 55 gallon tank I am wondering since it is only fish only do I need to get some sort of mechanical filter or would the live rock do I have about 30 pds live rock. I am curious abou this because I keep hearing not to use a mechanicla filter on a reef tank bit not to much on a fowlr

Do you have a sump? What fish do you want to keep?

No sump yet I am just getting some ideas before I put it together on what I need

Unless you are going to have big messy fish I would just go with 65-70 lbs of LR, a DSB and a HOB skimmer. You could add a cannister filter if you are planning on messier fish.

mech filtration has its uses, however if your starting out fresh, personally i wouldn't actively buy one. If your going to stay the FO route, then id think bio ball chamber & Phosphate reducer, if reef is somewhere on the cards, id try to stay with natural filtration in the way of rock & sand as carmie suggested.