Correct storage of tilapia feed is critical. You don't want to run out but you also don't want to store too much. There are a few reasons for this. Like anything the commercial fish foods have a expiry date. Obviously opt for sacks with the longest date possible. Also, as mentioned previously opt for specially prepared food which is suitable for the age of your fish. This will result in the best growth rate possible.
The tilapia food we bought came in sacks weighing 25 kilos. Now neither myself nor my husband are spring chickens but between us we managed to moved them. We just carried them but if you are going to move them any great distance, consider using a wheelbarrow. Here in Brazil, it is not uncommon to see men carrying this weight on top of their heads! I have even seen someone deliver a refrigerator by carrying it on their head. Sorry, I am going off topic, a bit.
The food should be stored somewhere dry and well vented. It also should be raised off the floor. Using pallets is ideal for this. It is also a good idea to put down poison for rats and possibly some cockroach bait boxes. You will be spending a lot of money on fish food, so protect it from animal or pest infestation.
It is a good idea to keep the area swept clean so you can see any droppings left by pests.
As with anything which has a shelf life, always rotate your stock so you are using the oldest first.