Sorry about the loses Caryl , but the 404 fliter is a good idea, it will have heaps of "good" Bugs to start the cycle with a hiss and a roar. Clean the tank completel first, add the 404 and rebuild the hideing places , you will have to watch for ammonia spikes so dayly water changes will be needed as it cycles. Good luck, and the yellow babies are your silver lining to a nasty black cloud
If you lived closer we could house them till its cycled.