Clucky

I just found out one of my Guppies passed away from it. How do I avoid them getting it? I feed my fish whatever they'll eat in 3 minutes every morning.

Ganal

How have you been feeding them? If you have just been sprinkling the food on top try mixing the food with a little water so that it'll sink. By feeding them under the surface of the water they can't swallow air with can cause problems.

Haris

ah. that may juat be the problem. you can't feed them on a strict time period. Okay. I'm not saying you should starve your fish but you can't feed them at exactly 7.a.m. every morning.

*and now the extremely long and boring speech begins*

In the wild, fish spend about half their time looking for food. And also, they don't always end up finding bloodworm. Or mosquito larvae. In captivity, these instincts remain.
Soooo, when you keep feeding them the same type of food at the same time, they stop foraging for food(even though it dosen't exist) because they know that they still get food.
This means of course that they lose half their excercise time and gain half their weight on pellets and flakes. Go figure.
Variety is also important. Goldfish are notorius pigs. They eat anything. I'd repeat the words 'anything' in capital letters but that'll probably seem to clise.
So, give them frozens (cyclop, daphnia, bloodworm, blackworm) but avoid tubifex worms. Unless you want a mutated goldfish with an extra human hand growing out of its brain giving you the finger while mouthing "YOU DID THIS!!!"
Dont forget vegetable matter like algae wafers or cucumber.