Leaving your aquarium shrimp unfed on vacation: what a fasting study shows
Published by Planète Pets · managing editor: Clément Lacaille · how our guides are written
Before a vacation, the feeding question comes up for dwarf aquarium shrimp just as much as for fish — but the answer is not the same. A 2015 study by Pantaleão, Barros-Alves, Tropea, Alves, Negreiros-Fransozo and López-Greco published in the Journal of Crustacean Biology measured fasting tolerance in the cherry shrimp (Neocaridina davidi) across developmental stages (, doi 10.1163/1937240X-00002357). General feeding guidance lives in the fishkeeping food section.
Contents · 5 sections
The "point of no return," a precise fasting measure
The authors used a standard indicator in crustacean biology: the PNR50, or 50% point of no return — the number of fasting days beyond which half the individuals die even if fed again afterward. They tested this indicator at three life stages of the cherry shrimp: the larva (zoea), the freshly metamorphosed young juvenile, and the adult.
A massive gap by age
The result is clear-cut: young juveniles have a PNR50 of about 16 days, versus nearly 25 days in adults. At the earliest larval stages (zoea), fasting tolerance is, by contrast, very low. The authors attribute this gap to energy reserves: a young individual, having just used up the reserves accumulated in the egg, needs to grow fast and has little margin, whereas an adult can draw on its own body reserves for longer before deprivation becomes irreversible.
What this means for an ornamental shrimp tank
A well-established tank of adult cherry shrimp, with biofilm and plant matter available on the glass, decor and plants, can objectively go one to two weeks without added food without putting the adults in immediate danger, based on the order of magnitude measured in this study. The picture changes completely for a tank with juveniles recently released from their mother's abdomen, or with larvae: their safety margin is markedly shorter, and an automatic feeder or a neighbour stopping by to feed becomes more relevant, much as we recommend for fish in our guide on a two-week vacation.
What the study does not show
It was carried out under laboratory conditions, with individuals completely deprived of any food source — a mature, planted tank with active biofilm offers a more favourable context than a total, controlled fast, which likely makes the real margin in an aquarium more comfortable than the study's raw figures. Nor does it measure the effect of repeated fasting episodes over a year, or reproduction after a prolonged fast.
Frequently asked questions
Can you leave adult shrimp unfed for a week?
In a mature tank with biofilm available, the order of magnitude measured in the study (PNR50 close to 25 days in adults) suggests a comfortable margin for a week, provided the tank is already well established.
Should baby shrimp be fed before leaving?
Yes: their fasting tolerance is markedly shorter than that of adults according to this study, so a meal or a feeding relay matters more for them. Find all our guides on the fishkeeping hub.
An accessory from our shop for this use: Ceramic pebble hide for shrimp and small fish (€20.90) · the whole shop
This guide is part of Planète Pets’s Fishkeeping universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.