The house as symbol
One might think that the two families are basically separated. They do not have to be viewed in tandem, but the novel invites that by having these two families share a home. With the home as a symbol, they are clearly a balanced image, like a yin-yang symbol, where the Pickles family represents randomness and chaos (they only have a home at all because of a random inheritance), and the Lamb family represents order and discipline. The novel plays on the ebb and flow between those two temperaments.
Money as a symbolic motif
Money is symbolic in the novel because these families are poor, so they are in chronic money crisis. The question on the table is therefore how they will handle their situation. With relatively less, the Lamb family transforms their fate by working hard to establish a local business that does well and pays their rent. The Pickles family spends that rent money on bad gambles and frivolous living. The moral insight from this balanced portrait is clear; to thrive, a person must simultaneously enjoy money and conserve it responsibility. Too much of one or the other can be unhealthy, as the families show.
Rose Pickles
Consider Rose's name for a moment. What symbol is more vibrant and instructive than a flower? And what is a pickle? A pickle is a dead fruit conserved by vinegar. Rose Pickles is a floral and life-appreciating person in a family of death and vinegar. This shows her as a symbol of hope, ironically, because she naturally finds a balance between the somewhat uppity Lamb family and her own irresponsible parents. As the only daughter, she also represents the desire to escape her family; she longs to be somewhere new.
Fish's motif
Fish is a young man who goes fishing and becomes injured. His injuries make him revert to juvenile psychology and behavior, which makes him symbolic. First of all, his name is Fish, but fishing harmed him, perhaps a symbol of self-criticism or self-critique? Secondly, he is a childish man, which makes him a symbol for the adult aspects of childhood consciousness and for the childish aspects of adult consciousness. The Pickle family leans more childish, and the Lamb family leans more adult.
Alcohol as a symbol
The Pickles family struggles with alcoholism, which would explain why the novelist picked that name for them. Their struggle with alcohol shows the symbolic dynamic of that drug, both in novels and in real life. The default setting of their alcoholism is that if there is a chance they could drink, that is what they will do. That means that they often spend their income on alcohol which basically prevents them from working hard enough to make a sustainable income. Alcohol is a brutal vice to them because it prevents them from admitting that they are unsustainable; they basically use the drug to ignore that fact.
