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As long as the fry aren't sick and their parents weren't sick, you could try. Did you try the garlic juice technique? Fasting procedures?
Fasting - Don't feed him for 2-3 days and see if he will eat. If he doesn't, take the food out. Repeat until he will finally eat his food.
Garlic Juice - Fast him for 2-3 days. If he won't eat, coat the pellets with garlic juice and feed. The juices will enhance the taste and smell.
What brand is your food? I recommend New Life Spectrum and Omega One. They're the best brands locally. Other good brands are Golden Pearls and Attison's. Bad
brands are Aqueon, Wardley's, Tetra, and Top Fin.