What clinical sign is NOT typically associated with Streptococcus infections in fish?

In the context of Streptococcus infections in fish, clinical signs often manifest due to stress, physiological disruptions, and underlying pathology associated with the infection. Signs such as spiraling swimming behavior, abnormal buoyancy control, and exophthalmos are commonly observed as they relate to the systemic effects of infections, impacting the fish's neurological and physiological functions.

However, hyperactivity is not a typical clinical sign associated with Streptococcus infections. Infected fish often display signs of stress and discomfort, which can lead to lethargy or subdued behavior rather than hyperactivity. Fish experiencing infection tend to exhibit more subdued or abnormal swimming patterns as part of their response to illness, rather than increased activity. Therefore, hyperactivity does not align with the expected manifestations of Streptococcus infections, making it the correct choice as the clinical sign that is not typically associated with such infections.