Chapter 27
Laws Relating to Animals on Shabbath and Yom Tov
FEEDING AND OTHERWISE ATTENDING TO ANIMALS
27.a. It is forbidden to change the water in an aquarium containing fish on Shabbath or Yom Tov.
27.b. If, however, it is necessary to add water every day, on may do so, even if the aquarium also contains aquatic plants.
27.c. The reason why it is permitted to add water Shabbath and Yom Tov is that the fish are dependent
on man for their food, and adding water is in the same category as feeding them, since, without additional water, they are liable to die.
27.d. There are good grounds for adopting a strict approach in treating an aquarium, together with the water and fish it contains, as muktzeh.
27.e. If one fears that the fish are liable to die without a change of water, one may request a non-Jew, even on Shabbath, to change the water, provided that, in the process, he does not allow the fish to be without water even for an instant.
28.a. A fish which has jumped out of an aquarium on Shabbath or Yom Tov may be put back to prevent it from suffering, so long as there is reason to suppose that it will continue to live when returned to the water.
28.b. There are, however, authorities who forbid this.
