Seems like you might have a nitrate problem. how much food do you give your fish?how long have the fish been in the tank? what is the nitrate reading(if you can't answer that question, you need to buy yourself an API master test kit.)
When was the last time you did a water change? When I neglect my water changes, algae always pops out to warn me. Nitrates can only be removed by water changes, unless you want to add unnecessary chemicals in your tank.
Algae and nitrate problems aside.....One flake per fish? Once a day? It sounds like you're starving them. Feeding them as much as they can eat for 3-5 minutes once a day is recommended. Even better yet, feed them twice a day for 2 minutes.
Your tank needs to cycle . You need to do water changes daily (possibly twice a day) until your parameters are right.
As far as the algae. Since you're not overfeeding your fish (actually you're not feeding them enough) it is probably a lighting issue.
Is the tank in direct sunlight?
How long do you leave the tank light on?
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