The Fish

I really want go fishing now!!  This poem is filled with happiness, despair, survival, and unadulterated joy.  Bishop's description of the fish is both detailed and beautiful; "He hung a grunting weight, battered and venerable and homely.  Here and there his brown skin hung in strips like ancient wallpaper, and its pattern of darker brown was like wallpaper: shapes like full-blown roses stained and lost through age."  This short little description lets the reader know that this fish is large, old, and worn.  This is no regular fish either.  He is a survivor.  "....then I saw from his lower lip -if you could call it a lip- grim, wet, and weaponlike, hung five old pieces of fish-line...."  Bishop goes on to describe them as "medals with their ribbons frayed and wavering, a five-haired beard of wisdom trailing from his aching jaw."  He has earned these medals.
I believe this poem speaks on strength.  It implies that the fish  has struggled and survived.  People have an incredible ability to "make it through" the tough times that life deals out.  Sometimes, we wear our scars proudly (the hooks and lines) and this allows others to know that we are survivors.  I was glad that she "let the fish go" at the end.  We can all only hope that, at some point in life, when our captors have us on the line, they will choose to let us go.  I believe , in a way, she compares herself to the fish.  "...victory filled up the little rented boat...."  I think this means she realized that they were both survivors and deserved to be set free form torment (abuse). 
Just a little end note to say that my pessimistic view-point on life was kind of hoping that she kept the fish and hosted a fish-fry later in the day!