I had my first spawn of bristlenose, they were almost a week after losing the egg sack. I have done plenty of water changes about every few days. I have been feeding plenty of zucchini, green beans, cichlid pellets, krill flake food, and some algae wafers. Also getting out food that has set for longer than 24 hrs. Today I did about a 50% water change and every single one of them are dead. Guppy fry in tank are doing just fine. What could be the cause of death? I do not want to make this mistake again. Thanks in advance.