From picture fry2.jpg looks like about 2 weeks old just as pointed out by
mkinga and
noahnjm.
The first 8 weeks of the fry's health will determine how well the fish will grow as an adult. Nothing is more important during this first 8 week than water quality. Second is a high protien diet that is essential to their growth. Pinned at the top of this forum contain an excellent source of information about
fry food.
Don't worry about cycling the tank for now. That takes time to establish. Unless you already have the sponge filter established with nitrifying bacteria, that task will take your attention away from caring for the fry.
So, instead of depending on nitrifying bacteria to neutralize the ammonia and nitrates, use a chemical water treatment available at the LPS instead. Amquel Plus or Prime work well for this purpose. They help detoxify any ammonia and nitrate created by the fish, their waste and uneaten food. This will give you time to let the biological filter to complete the cycle. If you don't already know the mechanics of cycling a tank,
Koko has a section specifically on the subject.
It is not a good idea placing the tank near a window for now. That will probably cause too much temperature fluctuation. Instead, place the tank in an area where there is little change in temperature. Sudden temperature change can kill young fry more than anything else. A submersible heater like the Ebo-Jager models (you can lay it horizontal at the bottom) are good for keeping temperature at a steady 75F. Also, you needn't worry about the height of the water now. After a week the fry's swim bladder should be well developed to handle deeper water.
Change water by siphoning out as much solid debris as possible into a suitable size bucket. Be careful not to suck up any fry. Place a finger at the other end of the tube just in case. Make a note of how much water is taken out and fill the bucket with the new water. Make sure the new water temperature and pH is the same. Siphon the new water into the tank through a small tubing. This will prevent any sudden shock to the fry. You can go about doing other things without worry about over filling.
If you must remove the fry to clean the tank, try not to handle them too much. No nets. Instead use a small measuring cup. Transfer some clear water from the tank to a clean plastic bucket. Siphon out water. When the water level is low enough, corral the fry into the measuring cup and transfer them into the plastic bucket. Clean the tank, place the fry back in, siphon in the new water slowly through a small tubing. Checking beforehand, the temperature and pH is the same.
Sounds like a lot of work but once you get a hang of it, it's a breeze.