Persuasive writing it best not to stray too far from a main point. Is this 2 pages handwritten or typed?
Also, you need to pick a side of the argument. If you want your topic of discussion to be large scale chain store fish, you'd look at the ethics behind staff misinforming customers about care needs, poor tank conditions and the overproduction of goldfish to meet consumer needs. Relate it to be about profit-hungry big corporations.
I'd suggest briefly mentioning that just because it's cheaper doesnt mean its better and that you pay for what you get. Well owned LFS
fish will be better quality - live longer. This can save money in the long run instead of replacing fish, and the customer service you receive at a reputable LFS
(in regards to teaching about cycles and managing fish illness) will save time and money invested in a relatively expensive hobby, that large chain stores can often not provide the same customer service as their focus is on mass production and selling, rather than meeting individual needs of customers.