HARTFORD, Conn. (AP) — A Connecticut aquarium has agreed to delay its acquisition of five beluga whales for research amid a lawsuit by an animal rights group trying to stop the delivery.

Mystic Aquarium will not import the whales before March 31 to allow time for a judge to decide the lawsuit and avoid an effort by Friends of Animals to obtain a preliminary injunction to stop the delivery, according to documents filed in federal court in Hartford on Dec. 23.

Friends of Animals, based in Darien, Connecticut, filed the lawsuit in September, saying the five belugas would be harmed by the trip fro...