He must be getting wholesale fish and treating them as a hobby and then realized there could be a small profit made.
That is exactly what I do, I buy wholesale and threat fish and sell them to clients that put in requests. I have been doing this for 3 years now.
I am a software programmer and own 2 businesses in Tulsa OK. This is simply a hobby and way to make sure most hobbyist carry healthy livestock.
I am not in it for the money and honestly it doesnt give me enough money by the end of the month either. I think the best i ever put in my pocket was closet o $900 in a month.
25% doa 25% mortality rate through qt and you are breaking even.
And i give out more free livestock than requested, I cover fish even after its been in clients tank for weeks. Ask any of my previous clients.
I am only in it to make sure livestock is healthy and please get to enjoy the fish without having to worry about parasites. That is why my prices are almost same as lfs or online retailer. (more encouragement for qted fish)