I once snorkled in a pond and watched a bullhead hide in a hole in the mud (not sure if they dig their own holes or not). I was thinking of this and when I get a biogger tank I may even try this idea if it is safe.

Would it be safe to use a PVC pipe section, buried in the gravel (except for one end) as a catfish cave? Would the plastic be safe and non-toxic for the fish?

PVC is completely aquarium safe. It's made for drinking water pipes. I have a PVC structure in one of my smaller tanks that's been there for several months, and lots of people do all the plumbing in their saltwater tanks entirely out of PVC. If you look around the tropical forums like aquariumadvice.com you'll find threads describing making these things presentable. The best idea I've seen is to smear aquarium-safe silicone around the outside and then roll it in gravel so you end up with something that looks fairly natural. I use bricks and flowerpots for caves mostly, and my catfish do appreciate it. One I have in a tank with no caves spends all day under the one piece of driftwood and almost never moves.

Point the entrance so you can look in

My yellow bullhead has some weird hiding spots in my tank, he'll hide in the rock caves, under the driftwood, but still he will hide behind the filter and wedge himself in there. He is very active, though. He is always swimming around to check stuff out and of course, eat like a pig. As for PVC safety, I know people who use it uncovered for fish caves in pike cichlid breeding tanks, they're ugly if you want it au naturale' but they work to keep those crazy cichlids from killing each other. I thin it look awesome if you covered it with rocks or little pieces of driftwood to make a hidey hole.

Edited by catfish_hunter, 07 December 2009 - 04:19 PM.