We have 2 Upsidedown cats that hardly ever come out. One used to hide inside a small crevase in the Barnacles that used to be the main decoration in the tank. the only way we could see him was by shining a flashlifht through a small crack in the front of the barnacle and looking for a fin outline, the barnacle has since been removed and replaced with Bogwood which gives him a dark place to hide, but we can still see him.
Lately we have discovered that if we put some frozen brine shrimp in just before lights out they will both come out to eat after the lights go off. We are also trying sinking shrimp pellets, the Banjo cat will unbury himself for these, even in the light, so we have hopes that the upsidedowns will respond as well.
Don.