Building a cave

what kind of fish? Some will not even utilize a cave. Slate works great for me. I have apistogramma cichlids that fit real nice inside a film canister. I cut a hole in one end push it into the gravel and put slate chips in front hide it. I do this to keep it from collapsing (not really a problem for an adult, but the eggs they lay inside would be crushed) Just using slate works good too.
 
Unless they are really sturdy, and especially if you have any bigger fish I would definately glue them together, just to be safe! But I'm a bit paranoid to soo... :joe: !! I've heard a couple of stories of a fish getting squished because a cave had collapsed, I would not want to come home to that :sad: !
 
Some fish also really enjoy coconut shells (either halved, or with just an end cut off so there's a large cave with a small opening), or clay pots. You can even coat the outside of a pot with silicone and roll it in dry gravel/sand to make a cave that blends in with your substrate :)
 
Those are both perfectly serviceable options Blinky. I've got nothing but respect for you, so please don't take offence when I say I find both coconut halves and clay pots (regardless of how covered with substrate they are) horribly offensive to my tank’s aesthetic appeal. No doubt I will use these options on future breeding tanks, but for a show tank... Slate is the way to go.
As for the gluing, it is a good idea when making teepee like caves, but I don’t think it would be necessary if they were stacked in a stable formation like the one in the picture (only not as many levels). It might become a problem when cleaning time comes. Alternately, you could glue some of the less stable pieces together in a kind of modular design.
 
*laff* absolutely no offense taken! Just because some fish like them doesn't mean they're suitable for your tastes or your tank, I just thought I'd throw in a couple more options, in case andy was interested :D
 
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