I had a few in a 20 gallon long years ago...thinking back, it was probably too small. It was a simple setup with an internal filter submerged on the right side of my tank where I had the water.
I ran the outflow pipe from the filter under the gravel and play sand and came out on the other side where it was land only. I laid out some pebbles along the path of the return water to try and make it look like a river.
I used brackish water with Kent Marine Salt Mix, added a submersible heater, and fed them bloodworms, silversides, and guppies. That was really about it.
I did not find them hard to maintain but I'm sure they would have been much happier in a tank like Jackiomy has set up...that tank is unbelievable.