Wow, that's a lot of eggs for three cories! I have 5 peppered in my tank with only one being a female and I typically only get around 12-16 at a time. Mine are crazy sexual deviants though so I have new eggs every 2-3 days.
If you want to raise them you need to separate them before they become caviar. I'm using this one and it's really nice, and since it's attached to the tank and uses the same water it increases their odds of survival:
Once the eggs are hard which doesn't take long you can pick them up with your fingers and stick them to the side of whatever you are moving them to. Make sure there is water flow where you put them or the could fungus over. An airstone will also do the job. If they start to turn brown they are doing well, if they stay white they didn't make it and will fungus over and can be tossed. Don't worry if they fall before they are ready to hatch, it happens sometimes, and they don't have to be stuck on the side to hatch, it just makes it easier to keep them from fungusing over. If you have rcs they will eat the fungus if it starts to form but won't hurt the eggs.
It could take up to 7 days but when they are ready they will fall from the side and hatch. When the hatch the tail will stick out and you will occasionally see the egg swim for a very small burst and then fall. They feed off the egg sack for the first 2-3 days and don't need to be fed. After that they need small high protein foods. I've been using frozen baby brine shrimp, but freshly hatched is great too. You'll know they are eating because they are fairly transparent at first and you can see a brown belly after eating frozen and pink after fresh. Also, if you have something like java moss put some inside as they will also eat the microorganisms that grow on it.
If you have them in a separate container put something like a snail in their to clean up any uneaten food. From what I've heard and observed so far MTS won't eat any eggs placed inside while other kinds will, although for me it only happened when I wasn't there to feed them one day.
I've been doing this for a few weeks now and currently have 20 fry all over the small tank with another 10 eggs developing.