I've recently added a figure 8 puffer to a tank with my pike cichlid and rainbow shark. He's been doing well for the past couple weeks I've had him. As far as temperament wise, the tank was semi aggressive with the shark and pike occasionally taking shots at eachother but that's all. I noticed the pike strike the puffer once when he was defending his rock but I see no spots on the puffer to indicate a wound. For a couple hours, the pike cichlid was breathing heavy and then started spazzing out of nowhere, and then died immediately after. I did a small water change but that's it, nothing out of the ordinary. I don't know if he died because of the puffer, because my water perameters are fine. Could the shark have striked him the wrong way and that caused his death? He was 3 inches and the shark is 4 inches. I just want to know what could have happened. We also have gravel in the tank but he never swallows it, he always spits it back out. Help!