look in my thread labelled catfish bonanza. I keep large rocks that cannot fit into their mouths, sand, and large pieces of driftwood mostly. I also get really large fake plants to go in with them as they tear the crap out of real plants. I plan out my tanks to have hiding spots. You can plan your tanks so that your fish' hiding spots are in plain view. In ponds put hiding spots wherever. Go with what you feel like. Just remember that big cats are curious, and will swallow anything that will fit in their mouths. Heaters are best if titanium when in the tank, and anything will work if you have an external sump you can put the heater in. Glass heaters are swallowed or broken very easily. Big cats are brutes, and if you don't aquascape the right way you could end up injuring your fish. I had a large rock in the tank with a rtc one time, and he broke his jaw ramming into it one night. Also my big hybrid swallowed some large stones that he sucked up when feeding. Just plan it out accordingly. Probably the best way to keep them for viewing, and for tank maintanence is bare bottom. No decor at all.