I know this is a stupid question but is that okay for the fish? Thats probably how much they eat in the wild right?
Hello; first thing is that fish are cold blooded and this generally means their metabolism does not burn energy at a high rate like people do. Fish who are at a healthy mass can go for a week or more without any food at all. I have left for up to a week and came back to fish in good shape.
Fish in the wild will feed when food is available but likely do not get twice a day regular feedings. At any rate it took me several years to figure out that I was over feeding. I now feed once a day and leave off feeding at least two days a week. I have been doing light feedings for a couple of decades or so. I have been doing fasting days for many years now. The fish do fine. One note: the exception to this sort of feeding is very young fry.
Even if the fish eat every single bit of food and there is no excess to decay in the tank, the food still is metabolized by the fish's gut and the byproducts wind up in the tank water.
Some fish are messy eaters in that they may take the food in the mouth but it gets broken up and tiny bits exit the gill covers.
My guess is it is the two a day feedings that are adding to the algae problem.