Infusoria and other similar foods are required for the fry for a minimum of three weeks, and it is not unknown for the fishes to take as long as twelve weeks to migrate to larger foods, growth rates being particularly sensitive to temperature.
To ensure proper development, fry require at least three weeks of feeding on infusoria and other similar organisms. It's also been observed that some fish may need as long as twelve weeks to switch to larger food sources, and their growth rate is highly sensitive to temperature changes.