The Question and Answer section for Sylvia Plath: Poems is a great resource to ask questions, find answers, and discuss the novel.
The slippery and unnerving "fish" in the poem may represent that unavoidable, darker self that cannot help but challenge the socially acceptable self.
It is not outlandish to assert that Plath's poetry might in fact be her crowning achievement. Bold, visceral, moving, evocative, wrenching, perplexing, and gorgeous, her many poems run the gamut from simple and charming to terrifying and violent....
This has nothing to do with your listed title. The add seems to state that parents must provide for their children's dreams if they really care about them.