I think that it is right to begin with the Theory of consumer choice. The above consumer has expressed his preference of choice. He has a taste for seafood which he prefers above all other types of food. This does not mean that he only eats seafood, but in line with the last two elements of the theory of consumer choice, he has shown his preference for taste and on that assumption, will do the best that he can for himself to consume as much seafood as he can. The elements of the theory which govern exactly how much seafood he will consume are the first two, namely the consumer's income and the price of seafood.
We can assume therefore, that the consumer will devote as much of his budgeted income for food, to as much seafood as he can afford in preference to other foods such as hamburgers.
A budget line can be drawn up to show a trade off between say, fish suppers and hamburgers to indicate the combinations of fish suppers and hamburgers the consumer can afford given his income and the prices of each meal. Points on the buget line will all be within the consumers budget for food. All points below the line will show the possible combinations of dinners avaiable for his choice. All points above the line wil be unaffordable. It will be possible to see how far the consumer could indulge his passion for seafood in one week.
(Slope of budget line = -Pu/Pv)
The next considerations that might be taken are the marginal rate of substitution of one meal for another without changing the total utility, the diminishing marginal rate of substitution which will hold utility constant and representation of taste as indifference curves. I will not elaborate on these at this point as I believe that the marginal utility and diminishing marginal utility are more relevan ...