Fasting new fish for 3 days after they enter the pond is a key measure to help them safely adapt to their new environment and reduce risks. The main reasons are as follows:
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Allowing Recovery from Transport StressDuring transportation, koi are in a state of high stress, and their digestive functions are nearly halted. Feeding them immediately can cause food to accumulate and ferment in their intestines, easily leading to enteritis or dropsy.
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Concentrating Energy on Repairing DamageFasting allows the fish to focus their energy on repairing mucosal damage to their gills and intestines, while also expelling accumulated stress toxins from their bodies.
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Avoiding Secondary Harm from Water Quality ChangesNew fish need to adapt to different water conditions (such as changes in pH). An empty stomach reduces metabolic stress and lowers the risk of shock due to sudden water parameter changes.
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Facilitating Observation of Potential DiseasesThese 3 days often coincide with the incubation and outbreak period for parasites (such as Ichthyophthirius multifiliis, or "ich"). During fasting, fish are less active, making it easier to observe abnormal behaviors (such as rubbing against objects or gasping at the surface). If issues are detected, timely isolation and medicated baths can be administered.
Notes on Resuming Feeding
Starting on the 4th day, feed a very small amount of easily digestible food (such as wheat germ feed soaked in EM bacteria). Observe their feeding response before gradually increasing the amount, returning to normal feeding after about one week.
In Simple Terms: Fasting for 3 days is like giving new fish a "rest and adaptation period," allowing them to safely pass through their most vulnerable stage and lay a foundation for long-term health.
