they do best in a seagrass-type/live macro setup. they'll use the plants for hunting as well as hitching ('gators are actually considered a "pipehorse"). i'd keep them at tropical SH temps (74*F). flow is OK, but nothing crazy.
'gators are usually one of the easier pipes to get onto frozen. they'll take baby guppies, mollies, or ghost shrimp in a pinch.