Seaside-caught small crabs can't be kept alive in fresh water.
The small crabs caught on the beach should be raised with seawater, not fresh water, feed the small crabs once a day, not in the sun. The home raising medicine with pots to raise, pots can put some fine sand, forming a small platform. The water used for feeding should not be too deep, the best depth is water just soaking through the crab's shell.
Crabs are omnivores, if possible, you can feed red nematodes, you can feed egg yolks, of course, crabs can also eat chicken and duck offal or small fish and shrimp. At the same time to feed some grass type of food.
The feeding intensity of crabs increases or decreases with the change of season and water temperature. In summer and fall as the water temperature rises above 15℃, the feeding ability of the crab is enhanced, which is fed once a day. When the water temperature drops below 15℃, the feeding ability of crabs decreases, and feeding can be done once every other day or several days. It is better to feed in the evening, because the crab is a diurnal aquatic animal.