I don't know the size of your fish, so here is part of an article I read and the link to it below.....let me know what you find.
Stocking Capacity of a Marine System:
The first thing you will probably need to know is how many fish you can keep in a particular sized aquarium. The most common formula for the amount of fish you can safely keep is based on the number of gallons of water in the aquarium. For a marine aquarium the formula states that you can:
1. Keep 1 inch of fish for each 5 gallons of water.
This simple method doesn't take into account the surface area of the water (for oxygenation), the filtration system (for removal of wastes), and the general size of the fish. For instance, a fish that is 6 inches long needs a lot more oxygen than 6 fish that are 1 inch long. In general you should reduce the amount of fish if they are larger, and increase the amount of fish if they are smaller. Another method is to:
2. Calculate the surface area of the aquarium and divide by 48 to get the number of inches of fish the aquarium can handle.
This method takes into account the aquarium shape but not the filtration or the size of the fish. The second formula favors aquariums that are shorter and wider i.e. not 'showtanks' which are taller and skinnier.
In general the more complicated formulas are not worth the trouble if you don't approach the maximum number of fish calculated by the above formulas. Perhaps if anyone shows interest, we can write more on this later.
http://animal-world.com/encyclo/mari...tm#inhabitants