- A high protein (>50%), low fat treat food which aids koi and other large pond fish to gain weight rapidly. Silkworm pupae also contain high levels of calcium.Silkworm pupae are a high source of protein which contributes to the rapid growth of fish. Feeding silkworm provides a better slime coat protection to resist parasite & bacterial infections resulting in a better, bigger healthy fish. Silkworm isnaturally high in protein, calcium, nutrients, vitamins, minerals & other essential fatty acids.