This is a tough business. The things that stand out to me are "specializing in 2-4 types of fish" and "selling in my area". If you are only selling locally you are basically a LFS even if you don't have a storefront. If you only have a handful of types that is pretty difficult. Each box has a fixed cost to get to your pickup point so most people either pack that box as tight as they reasonably can to spread that cost, or buy the most valuable fish they can to overcome that cost (or some combination of the strategies).
Using transhippers is certainly a route to go and probably the best for now, but IME most transhippers don't want to break up and repack fish. Therefore you are going to buy a full bag (300 neon tetras, 100 banjo cats for example or 50 2" Dovii). Then you are stuck holding them until you can get them sold. Mortalities are part of this. Fish are going to show up dead. Who is responsible? If you have a live arrival agreement that is great, but even then if the fish "haven't died yet" you are going to eat that.
The true question is do you live in an underserved community that needs a quality store therefore you should open one and offer a wide range of fish? Or do you live in a community that everyone has analyzed and decided wasn't worth investing in at this time?
The only way I see this having any success with a limited number of varieties is to ship nationally and be the king of a niche. Be the guy to get wildtype bettas, discus, stingrays, or something else in Canada. This requires some good web skills and building a brand. You have to be both the source of knowledge and the source of fish. Ecommerce is a tough business sometimes and you are at the mercy of weather and at times unrealistic expectations of customers.
