How often should I feed my hermit crab and how much?
Adult hermit crabs thrive on 1–2 teaspoons (≈5–10g) of mixed food each day, plus constant access to fresh and brine water.
Daily feeding routine
Feed an adult hermit crab 1–2 teaspoons (≈5–10g) of mixed food daily. Offer a shallow dish of dechlorinated fresh water and a separate dish of marine‑grade brine water (3% salinity) at all times.
Place the food dish in the middle of the enclosure for 12–14hours, then remove any leftovers. This window matches the crab’s natural nocturnal foraging and prevents mold. A kitchen timer set for 24hours helps you stay consistent.
Adjusting by life stage
Juvenile crabs (0.5–1in, 0.2–0.5g) need ½ teaspoon (≈2–3g) of finely chopped food 2–3 times per day. Small portions keep the substrate dry enough for successful moulting and give the young crab multiple feeding cues.
Adults (2–4in, 5–15g) get the 1–2 teaspoons noted above, while seniors (4–6in, 15–30g) often eat slower and benefit from 1–1½ teaspoons (≈5–8g) once every 1–2 days. Reduce frequency if the crab leaves food untouched for more than 6hours.
Measuring, mixing, and transitioning
Use a digital kitchen scale that reads to 0.1g; 1g equals 0.04oz, so you can quickly verify the 5–10g range for adults. Mix a base of commercial hermit‑crab pellets (40% protein) with shredded carrots, spinach, and a pinch of calcium powder for a balanced diet.
When introducing a new protein source such as shrimp or boiled egg, start with 10% of the total mix and increase by 5% each day for 3–5days. This gradual shift lets the gut microbiome adjust without triggering digestive stress.
- 40% commercial pellets
- 30% vegetables (carrot, spinach)
- 20% fruit (apple, mango)
- 10% protein treats (shrimp, egg)
- Add 0.5g calcium powder per 10g mix
Water, brine, and treats
Provide two dishes no larger than 2inches in diameter and 0.5inches deep; change the fresh water every 24hours and the brine water every 48hours. Test brine salinity with a refractometer; aim for 1.020–1.025 specific gravity.
Treats should never exceed 10% of total intake. A ½‑inch slice of banana or a single pea counts as one treat. Offer treats no more than three times per week to keep calcium balance stable.
Common mistakes and how to spot them
Over‑wetting the substrate is the most frequent error; if the sand feels soggy after feeding, reduce water dish size or increase ventilation. A damp substrate can cause fungal infections and impede moulting.
Leaving food in the enclosure for longer than 6hours invites mold and bacterial growth. Spot mold by a white, fuzzy layer on the surface; discard immediately and clean the dish with a dilute vinegar solution (1part vinegar to 4parts water).
- Check substrate moisture daily
- Replace uneaten food within 6hours
- Refresh water dishes every 24–48hours
- Monitor salinity with a refractometer
Keep reading about Hermit Crab: Hermit Crab care sheet
Related questions
How much food should I give a 3‑month‑old hermit crab?
A 3‑month‑old crab (≈1in, 1–2g) does well with ½ teaspoon (≈2–3g) of mixed food three times a day, spaced about 4hours apart.
Can I feed my crab fruit every day?
Fruit should be limited to 10% of the diet, which for an adult equals about ½ teaspoon (≈2g) per day. Giving fruit daily can raise sugar levels and reduce calcium absorption.
What temperature range is safe for feeding?
Maintain the enclosure at 75–85°F (24–29°C). Feeding outside this range can slow digestion; if the temperature drops below 70°F (21°C), reduce feeding frequency by half.
Not veterinary advice. This guide covers husbandry — housing, feeding, cleaning and handling. If your hermit crab is injured, off food unusually long, or behaving abnormally, contact a veterinarian.