First off, how do you plan on running your set up? are you going to set up a sump below your tank? Are you going to use all hob (hang on back) equipment?
I suggest using some live rock in your tank, the Moray eel is an ambush predator who's natural habitat is within the cracks and crevices of the reef. Creating many caves and crevices will allow your eel to have places to hide, but the rock should be placed securely, so the eel can not knock it down. Live rock also acts as a natural filter element to break down ammonia in the water column.
If you do not want to put rock in your display, and you plan on running a sump, I suggest placing some live rock in your sump to help with your filtration.
That being said, eels are very messy eaters and as large predators they produce a lot of waste. A clean up crew (cuc) of hermits and snails are vital to removing the left over scraps of food and detritus in your tank. Some eels will eat hermits and snails, if hungry enough or just because. My snowflake eel would not bother with hermit crabs until they decided to switch shells. I also recommend some nassarious snails, because they bury themselves in the sand and will eat left over scraps of food. You may need to replace your hermits every once and a while, but they will cut down on the amount of waste in your system.
Basic equipment, you will need some sort of HOB filter to provide basic water turn over. Ideally you will want bare minimum of 10 times water movement (turn over). I reccomend a hob filter with two returns for filter media, so you can use one for carbon and the other if you want to add live rock rubble, or another type of filter media. A protein skimmer would be a nice filtration addition, but not entirely necessary. A florescent strip light and standard aquarium hood will be fine, fish only tanks do not require any special lighting. No matter what hood you use, you will need a top of some sort on your tank, Eels are natural escape artists and will manage to find their way out of most holes in the tank.
Your substrate should be a medium or small grained live sand. Eels tend to burrow in the sand so if you get something that is very fine grained your tank could be very cloudy. Do you want to have a deep sand bed or a shallow sand bed? Both have different properties, and their are pros and cons for both.
Now for the bad news. Your 55gal aquarium will be too small long term for a goldentail eel. The minimum aquarium size for this animal is 125gals. Eels can grow very fast, and if you plan on placing this type of eel in a 55gal aquarium you should plan on upgrading ASAP. As previously posted a snoflake eel would do well in a 55 gal tank long term. These eels are typically very docile and interesting to watch in the aquarium.
No matter what you do, good luck with your new hobby.
Prk543
Thanks.
