Vegetable matter like algae wafers and peas are not good for carnivores---actually, insectivores. Your first step should be to fast him for a day or two to see if he recovers his appetite and energy. He might get hungry enough to eat the shrimp, which are good for him. ;-}
Frozen daphnia or frozen brine shrimp are considered roughage/fiber to enhance digestion.
Frozen is much better than freeze-dried unless that's all you can get.
A varied diet, consisting of a couple types of good-quality pellets (protein source as the first ingredient) plus bloodworms every few days and occasionally daphnia, is optimum, but you don't have to get carried away.
In any case, as with all pets, it's good husbandry to monitor his feces.