I am a native on Bangor and through my travels I found Vance's tropical fish in Bucksport. It is an excellent store and worth a little drive to get to. Usually Vance will be around the store and introduce himself to customers, very nice and knowledgeable guy.
The store is not particularly big, and the emphasis is on live stock more so than equipment. In fact the equipment section is almost nonexistant although I think Vance does a lot of custom carved tank furniture. However the live fish and plants are kept very healthy and there are a lot of things you won't find at the chain stores, plus you might be able to arrange custom orders.
However the place is an experience. Vance has recently started travelling to Hawaii and making his own handcarved Hawaiian guitars, and the entire store is thoroughly decorated with a Hawaiian beach feel. He has a big display lagoon that takes up an entire room and was formerly the home of a nurse shark though I think it's smaller fish now. There is a shallow open-topped display reminiscent of a touch tank full of shrimps and crabs and interesting critters. He also displayes his hand carved wooden guitars, tank furniture and such.
Very cool place overall (although it's pretty small) and a very honest businessman. I've been a fan for about 10 yrs now and even though I live in Mass I try to make it over there when I'm up visiting my folks.