Aeromonas salmonicida, a Gram-negative bacteria, causes the disease furunculosis in marine and freshwater fish. Streptococcus iniae, a Gram-positive, sphere-shaped bacteria caused losses in farmed marine and freshwater finfish of US$100 million in 1997.[50] Myxobolus cerebralis, a myxosporean parasite, causes whirling disease in farmed salmon and trout and also in wild fish populations.