I had a pair for several years. I like this fish very much, thinking it is time I get another pair. The species is in our profiles with good accurate information [and no, I didn't write this one
As it says there, they remain at the surface; they will jump, one of mine jumped out once and I was amazed that after several minutes it survived when put back in the tank. They will eat any fish that approaches the surface, and their mouths are very large--the entire front part of the fish opens up. They need soft acidic water, and floating plants. Anubias, Java Fern would make suitable lower plants as the floating plants should be fairly thick but provide open space between for maneuvering. They will lie motionless for hours, but drop in an insect (house flies, beetles) and wow! They do best in a pair, or a group. Male and female are easily discernible by the quite large anal fin; on the male it is distinctly notched with extended centre rays--you can see this in the third photo in our profile, which is a male. The female's fin is basically rounded.
They have a nice social interaction when kept in a pair or a group, and I highly recommend this because otherwise they will be very dull. They really are motionless on their own. They don't need much room; I had my pair in a 15g which provides surface area but is shallower and except when threatened, they will not go below the surface. Bottom fish, also well suited to shallower but longer tanks like a 15g or 20g long, could be any that are non-aggressive--pleco, whiptails, etc. Corys that regularly breach the surface might be risky, the Pantodon would likely respond to the quick motion and possibly grab the cory and cause damage even if it couldn't actually swallow it.
Minimal filtration, an undergravel or sponge filter works well, there is no need for currents or surface disturbance as this fish occurs in swampy pools. I fed mine from my fingers, they became quite used to me. Mealworms (both the worm and bettle, I was raising these at the time for my amphibians), chunks of frozen foods like beefheart, squid (excellent nourishing food, squid), freeze dried shrimp. If the food floats they will usually grab it, especially if it moves a bit, sometimes I used to use a piece of broom topush the chunk and wham! gone in a flash.