It is INCREDIBLY hard to get fry to survive to adulthood in the same tank as the parents with any great success. If you add lots of hiding places like plants, gravel, sponges and breeding mops you will have more fry surviving, but this works better in bigger tanks. You certainly have to block the intake on your filter. Have you checked inside the filter? if they aren't getting eaten by the parents they are probably being killed by the filter. You can block the intake on the filter with a sponge to prevent this from happening. you can use any kind of filter sponge found at the pet store (NOTE: this will reduce the flow of the filter and make it not work as well & you'll have to clean the sponge regularly) I've found that the best way is to remove the fry as soon as you find them, put them in a small tank of their own (making sure the filter intake is blocked) and let them grow in there until they are just big enough to not fit into the mouths of the parents. then its safe to throw them back in with the parents. otherwise good luck preventing them from becoming dinner for the parents when their tiny. I used a 2.5 gallon hex tank as my fry nursery. they only have to be in there for a month or two. I fed them any kind of tropical flake food that i would crush into a powder a few times a day. Give them TINY amounts of food. They dont eat much and because you have the filter intake blocked the tank will get dirty quick. Regular water changes are ESSENTIAL to proper growth. Its fun to have them in their own little tank for a while and watch the little grains of rice grow into little fishes.