While I also will choose not to disclose what the exact margins are to protect local stores I will say that according to NYU surveys of business across the US in 2020 the average gross margin for specialty retail is between 28 and 29% This is in line with the aquarium hobby which is closer to specialty retail than anything else in their break down.
It is ridiculous to not consider net margin. Otherwise financial services like banking would look great because they have close to 100% margin. Not knowing the net margin can be a big problem for stores. When I was at the LFS I was under the impression that I was making more money on livestock than dry goods but after doing a cost analysis of extra employee hours, salt, food, losses, electricity, and water I found that the net margin was about the same as with dry goods. Dry goods sit on a shelf, don't die and most don't expire. The overhead cost of X square-foot of dry goods compared to X square feet of livestock is huge. Live stock has far more overhead.
It is ridiculous to not consider net margin. Otherwise financial services like banking would look great because they have close to 100% margin. Not knowing the net margin can be a big problem for stores. When I was at the LFS I was under the impression that I was making more money on livestock than dry goods but after doing a cost analysis of extra employee hours, salt, food, losses, electricity, and water I found that the net margin was about the same as with dry goods. Dry goods sit on a shelf, don't die and most don't expire. The overhead cost of X square-foot of dry goods compared to X square feet of livestock is huge. Live stock has far more overhead.