If you are of the “go big or go home” school of thought and are determined to have one of the larger moray eels, the first aquascaping decision – the size of your tank – will be determined by the species you choose to acquire.
You will certainly be working to control some behavioral knowns. Morays are:
All of these “knowns” are more easily managed in a tank that is the appropriate size for the eel in question (preferably with room to spare.)
All eels are escape artists, so a secure tank with a lid to prevent daring escape leaps is a must. The following rules of thumb for space requirements are good guidelines, but you should do species-specific research for any eel you plan to house.
One good way to do this is to join an aquarium discussion board and simply say, “I’m thinking of keeping a Snowflake Moray Eel. Any suggestions on aquascaping?”
Such forums are an excellent resource for “real world” advice from enthusiasts who have already tried certain arrangements and have a sense of what does and does not work with the species you’re considering.
If you do not have a species in mind and are still trying to select an eel, consider the following rough approximations:
A good book for anyone thinking about keeping eels as pets
Good job explaining aquarium “eels”, Moray’s, Spiny, Eel-Like fish, and misc. eels. Very good information on creating the aquatic environment with a special section about Moray tanks. A good guide with helpful information covering much of what I wanted to know.