From what we read online it said about 1 year. After we bought the tilapia, hubby was doing more research and found a guy in Florida that said 2 years before harvest. I know they will NOT survive the winters outside. We thought that we would have been able to harvest them before winter (from what we read before we got them). We actually just have them in one of the blow up pools outside. It's about 3,000 gallons, We bought a I think it was a 12 foot blow up pool for them. We had a huge home made pond for the koi but it sprung a leak and we couldn't find the leak and lost a ton of koi.
Over the winter, in the basement, we had them in one of the little 6 foot blow up pools. They did great and actually bred in it. They grew very nicely in it as well. I have the blue tilapia. They are more tolerant of colder water, so it gives us some time to get them in for the winter. Of course we want to keep a breeder group so we can have more tilapia growing out when we want more! I can't wait to eat them lol.
This picture was from over the winter of our inside set up. This winter we are doing things differently, We are building wooden boxes for them to go into. Takes up less ground space and we can go higher for more gallons. If there is a will, there is a way. Taking pictures of fish is so hard for me lol We had some minnows in this pool with them. I will update you on the size they are now when we catch them for the winter. They I would guesstamate around a foot long for the most of them, some are smaller.
This is a picture of the pool outside now with the koi.