mudskippers

Sand, not gravel
 
Here is a great place to get "LIVESAND"
If I was going to setup a tank for mudskippers I would first put a layer of Mineral Mud mixed with some Onyx Substrate, then I would mix some Marine BioSediment with LIVESAND. The majority of the substraight would be livesand.
I would then be able to plant mangroves and there would be a whole ecology setup already for fish to be added.
**Livesand is for saltwater.
You can lower the salinity slowly to high-brackish I wouldn't go below 1.012.
 
AquariaCentral.com