29 gallon ?

What size tank what I need for those fish?

 

Skip the cardinal. Clowns are fine. Blenny is cool too. Look for a smaller goby. I have 4 fish in a 34 and some days I think it's too much. I also have 4 in a 40 breeder and plan on adding 1 more. If you want that many fish look for a 55+ with a larger sump.

 

The place I want to put the tank is only 31.5" wide

 

A 24" cube would be about 60 gallons and fit in that space.
Even 60 gallons is probably too small for 9-10 fish though. You have been receiving good advice here.
Due to the biological filtration in a saltwater system you can't load them up with fish like you can with a fresh water system with lots of mechanical filtration. Theer is only so much area to grow the beneficial bacteria that does the natural filtration.

 

I would go for a HOB reef octopus skimmer and skip the Live Rock. For fish only tanks, coral inserts are the way of the future and can end up costing around the same as primo LR

 

Well, the rock plays a significant factor in bio-filtration, so it's not just for looks. Having said that, go with dry rock, not live.

 

I agree but the (de)nitrying bacteria in/on rock can be acheived in other ways...

Tough part is if you are buying primo LR, odds are that it will have life on it which will require dosing and proper lighting to maintain...

That's why I would just get coral inserts or better yet, just build a reef if you are going as far as to put LR in your system

 

Of course. I wouldn't buy live rock if it were me either. However, if he/she has plans on a heavy bioload, he/she will need every available pore that the 60 lbs of rock will provide in addition to whatever mechanical filtration he/she plans on using. Maybe add some inserts to that for aesthetic purposes?

 

Coral Inserts or fake coral does not have the pores<sp? nature that rock has. Good live or dead rock will will have way more surface area for bacteria than fake coral. If you want to add it to pretty things up fine, but I would still add the base rock, not live.