Animal rights activists have gone to court in an attempt to block the trade of an aggressive dolphin from the New England Aquarium to a secret Navy training center in California. Opponents of the swap claim the Navy trains dolphins for hazardous duty. A lawsuit seeking to block the trade was filed Monday in federal court by Steven Wise, an attorney for Citizens to End Animal Suffering and Exploitation. He said a hearing would be held Wednesday or Thursday. The aquarium wants to trade Rainbow, a 450-pound male, to the Naval Ocean Systems Center in San Diego, Calif., for a partly deaf female dolphin. The Navy center said it trains and studies 142 marine mammals in underwater surveillance and other activities. Opponents say the aquarium lacks the required paperwork for the trade.