This flexible system provide enough protection to Nile tilapia (Oreochromis niloticus) during cold weather in Egypt and in the same time allows fish to disperse in the pond and feed whenever weather gets warmer. Overwinter greenhouses are placed in earthen ponds whereas plastic covers go well below water surface but not reaching pond bottom. The area beneath greenhouses will be protected against cold winds and act as shelters to tilapia. Whenever, weather warms up as the case in sunny days, fish have the choice to temporarily swim away the green house and grazes natural food or feed artificial feed as shown in the photo with a demand feeder. This type of overwintering facility does not interrupt farming operations whereas fixed parts remains uncovered during warm months and are covered only when cold weather approaches (this is seen in the second photo).