Yield

How large would a fish tank for a group of 10 or 30 have to be?

Offered by Jan.

If you have fish that are able to multiply every month with success, and you are with 30 people and each eats two - three fish a week then you will consume in total between 60 - 90 fish a week. That is a lot of fish. One fish a week per person would come down to a total of 30 fish per week and 120 every month. If the fish is about the size of a general human foot and about a general hand thick then that would do fine. So the type of fish you should be keeping must be:

1. freshwater
2. fast breeding
3. fast growing
4. not picky with food (a lot of fish types are)
5. insensitive to fluctuations in temperature
6. not needy of a lot of space
7. not too small (about 20 cm and up)
8. resistant to many diseases, has to be a strong type
9. insensitive to fluctuations in water pH and dH. (acidity and hardness)

The above are important factors for providing a consistency in the supply and quality of this food resource. Best thing to do is to look at the type of fish that fish farms breed where freshwater fish is concerned:

1. Salmon
2. Trout
3. Tilapia (subtropical)

then there are other types of animals that can be grown and bred in captivity as a food source:

1. fresh water prawns
2. fresh water crabs (they do tend to eat each other though but need but small space each)
3. crawfish (type of lobster from fresh water), like the Australian yappie (again, might eat each other sometimes. Solution to that problem is having them in several different tanks or one tank divided in smaller sections).

I do not know how large the fish tanks should minimally be, it is very important that you know the right amount of fish per tank, as crowding will stop the fish from breeding and the water quality will deteriorate rapidly. Water needs to be oxygenated. You can do this by aeration, meaning you have an apparatus that blows bubbles from the bottom of the tank. For this you need an air pump. You can also get the same effect of oxygenating the water without the bubbles, but then you need to have the surface of the water in constant motion. A water pump is needed here where the water is pumped into the tank from above, breaking the surface of the water. The water needs to be in constant motion and needs to be filtered. Filtration can be done mechanically via a water pump pumping the water through a filtration tank, or biologically by letting the water flow from the fish tank into a tank with plants where the organic substances in the water are used by the plants to grow (so you need light here too).

Offered by Michel.