reds are pretty undemanding , keep at tropical temps , carry out SMALL but regular water changes (they hate large changes) ,they will apprechiate some form of floating plant cover ,they seem to feel much more secure with them , start them out on bloodworm, mysis ,small peices of lance fish ect ,keep the deit varied or they will become addicted to a certain type of food , due to the types of food they eat a large filter is recomended (think nearly double the normal amount.
they can be started out in anything from about 4ft x1ft x 1ft ,but as they grow will req much larger quarters , width being just as important as lenght hight is not so important but no less than 18" , given enough space reds often accept tankmates , the trick here is to start them out around the same time as the reds and finding things that will not outgrow the red and the reds will not outgrow , many people have had sucsess with gars , birchirs , certain catfish , or middlewater swimmers that are not overly aggresive and grow the same sort of size ,i.e pacu ect , however the more of these true monsters you add the bigger the final tank would need to be.
what size tank do you have and what size are you planning on getting , there are over 30 species of snakehead and another type may suit you much better (just a thought)