Pre selling and creating a market for your items would really help. Speaking at local fish enthusiast / aquarium societies meetings, offering product demos in new and unusual places. Like farmers markets, Business promotion days like at most towns and cities have a celebration on one or more times per year where there is a fair, end of summer celebration, founders day type celebration, 4th of July fireworks parties, offering demos at a lfs.
Using social media effectively.
Knowing everything you can inside and out, sharing info with forums, finding a balance with providing information with promoting your product. Finding ways to integrate your products into the minds of your customers, or your clients customers.
Customer service!!! To either your clients or your vendors.
Showing display tanks with your featured fish, (products), like a restaurant, Dr. office, School, etc., demonstrating and showing how they are desirable and how the average person can have success with YOUR great products.
Good luck!