really 0 is to many for a 55 but a lot of people break this rule i have two in a 55 people tell me i am crazzzzzzzy but i am stubborn and crazy i guess if you must have one go with a smaller species like a yellow eye and get one that is small good luck this rule can be bent it is really a decision only you can make but if you get a small specimen he should be fine for a little while
( i realize i may have said some things that conflict with other peoples opinions but lets please not make this into a flaming cession)