Molting Care for White Shrimp — The Hours After a Molt Are the Riskiest

Shrimp do not grow gradually the way fish do. They are locked inside a rigid shell, and they get bigger only in the moment they shed it. Molting is growth itself. The problem is that it is also the most dangerous time in a shrimp's life. ■ What happens right after a molt A shrimp that has just shed its shell is soft. The new shell takes roughly one to three days to harden, and during that stretch the animal is effectively defenceless. Predators are one threat, but so are the other shrimp in the same pond — a soft-shelled neighbour is an easy meal and a convenient source of the minerals they need for their own shell. This is why losses cluster around molting in dense ponds with nowhere to hide. Oxygen is the other thing farmers miss. Molting burns a great deal of energy, and oxygen demand rises sharply while it happens. A dissolved oxygen level that is normally survivable can fall short during a molt. Hold DO at 5 mg/L or above, and pay particular attention to the pre-dawn hours when oxygen bottoms out. ■ When the shell will not harden — molt failure Building a new shell draws minerals from the water. In water with low alkalinity the shell cannot harden properly, and animals begin a molt they cannot finish. That is molt failure. Manage alkalinity in the range of 100–150 mg/L. The same buffer also stabilises pH. When alkalinity runs low, the daily pH swing widens, and that alone is a burden on the animals. Sudden salinity changes cause molt failure too. White shrimp tolerate a wide band, roughly 5–35 ppt, but what matters is not the absolute value — it is the rate of change. A shift of more than 5 ppt in a single day is more than a freshly molted shrimp can absorb. Always re-measure after a water exchange or heavy rain. Keep the daily temperature swing under 3 ℃ for the same reason. ■ Do not feed more when they stop eating As a molt approaches, shrimp eat less or stop altogether. This is normal, not illness. The common mistake here is to read the reduced intake as hunger and increase the ration. Uneaten feed settles on the bottom, breaks down, drives ammonia up and consumes oxygen. During a molt that means causing the two things you least want, at the same time. Reduce the ration and adjust based on what is left in the feed trays. ■ Give them somewhere to hide The single most reliable way to keep a freshly molted shrimp alive is to keep it out of sight. Ponds with adequate shelter lose noticeably fewer animals during molting periods. In high-density ponds this matters more, not less. ■ You track molting with records, not with your eyes A pond does not molt all at once. Individuals are on their own schedules — younger shrimp molt more often, larger ones less. So "are we in a molt right now?" is not a question a single look at the pond can answer. Records answer it. If feed intake has been falling for several days, empty shells are showing up on the bottom, and mortality ticked up over that same window, molting is likely involved. Log feeding, water quality and mortality against the same dates and you will start to see the next cycle coming. Shrimp365 logs water quality, feeding and mortality per tank and alerts you when a value leaves its range. It is free to use.