Lava rock as decoration?

Hello,
I am getting my 30 gallon, newly cycled tank ready for some fish...but as is usually the case for me, I jumped right in without really thinking much about appearances (I figured, the cycle is the longest process - I'd do that first, and decorate later).

So now I'm trying to figure out decorations - I have a lovely piece of driftwood that just needs to be chopped down to size and sterilized, but I'd like some rocks to go with it. I was thinking lava rocks, glued in place to give the fish hiding places and swim throughs.

But then I read that apparently cory cats can hurt themselves on it, but those people seemed to be talking about using it as a substrate rather than as decorations (we used pool filter sand as substrate). Would they be ok with some decorations made out of lava rock, or should we start looking at other types of rocks? The "aquarium decoration" fake rocks are all overpriced, in my opinion...and they usually stick tacky looking fake plants on them to boot, so I'd just like some plain, cheap rocks, preferably that I can arrange myself.

I've also considered river rocks, but feel like gambling on rock composition isn't really worth it for me.

 

Are you looking to buy?
Also they should be okay to use.

 

Are you looking to buy?
Also they should be okay to use.

Yes, I was looking to buy.

Was planning on just getting bbq lava rocks from the hardware store, but if they're known to have unsafe additives Big Al's isn't *too* far away, and I know they have large bins of decorative rocks.

 

Shop your local rockyard or landscape company. You'll find a huge selection of rocks, that are clearly identified. Most varieties of rock sell from twenty five cents to 35 cents a pound in my area.
Medium sized rounded river stones would go fine with Cory Cats.

 

Let's take a look at Pisces Seiryu Rock. I read a lot of positive reviews about this type of rock.

 

I'm using natural lava rocks I found in my local mountains, and my cories eat food off them all the time. But since they are large rocks, food sits on top, rather than getting stuck in between. I can see how using smaller lava rocks as substrate would erode their barbells.

 

I use black lava rock all the time. I buy mine from Home Depot. I usually buy the xxl ones and the medium ones.

 

Lavarock is perfectly fine.

Corydoras are armoured.catfish. They aren't made of wax and not stupid.
What you have to prevent is that (all kinds) of fish don't panick and wedge themselves between te rocks.

Fish have sensory organs that prevent bumping into things etc..

 

Let's take a look at Pisces Seiryu Rock. I read a lot of positive reviews about this type of rock.

If it's real Seiryu rock it buffers and raises hardness and pH. Nothing one would want in a corydoras tank.

 

If you don't mind paying for the rocks, I really like Dragon Stone. I really like the multiple colors and shades in each piece and it has really interesting little holes and divots. I can typically find it for about $2-3 a pound at various local fish stores. Pricier than some of the other options listed here, but compared to some of the other expenses in the hobby...not bad at all.

Here's a picture of some that I have in my 55 gallon.