How can you tell if aquarium decor sold at a pet shop is truly safe? I once had a pretty standard looking piece of decor fall over and possibly injure a pleco. I guess the pleco must have knocked it over even though I thought I had the base buried under enough gravel.

Just a word of advice, don't buy your aquascaping material from your local fish store. The gravel in my tanks are small grain pool filter gravel, and pea gravel. Both available at Lowe's and Home Depot, cheap. My hardscape is Texas Holey rock, $3 a pound at the local fish store, 20 cents a pound at the rock yard. I bought 250 lbs. Most of the ceramic and plastic decor are made in China. Not what I'm looking for.