Maybe it's the diet. You'd better feed it more kinds of food (but the quality must be good, you can ask others, I'm not particularly good at this). I wonder if your fish eat that kind of bug. It is white and very nourishing. If it's safe, it doesn't matter if you feed it every other week for five days. But don't feed too much at once. One fish 1/3 worms at a time is enough. Don't feed too much at a time, it will cause problems.

Of course, it is good to raise aquatic plants, but the survival rate must be high, otherwise the death of aquatic plants is not good for fish.