are silver dollar fish aggressive

[Griffin]

Based on the provided information, Silver Dollar fish (Metynnis argenteus) are overwhelmingly characterized as a peaceful and non-aggressive species, making them suitable for community aquariums. Their typical disposition is described as timid and skittish, particularly when they are not housed in sufficiently large groups. To mitigate this natural nervousness, it is recommended to keep them in schools of at least five individuals.

While not predatory or territorial in a conventional sense, they can exhibit behaviors that may be misinterpreted as aggression. As herbivores, they are known to be destructive to live aquatic plants, which they readily consume. Furthermore, their active nature may lead them to nip at smaller, slow-moving fish, though this is not considered a defining aggressive trait.

However, it is important to note that individual temperament can vary. There is anecdotal evidence of a Silver Dollar fish displaying highly atypical and extreme aggression, unexpectedly attacking and killing its tank mates. This account appears to be an exception rather than the rule for the species, suggesting that while the vast majority of Silver Dollars are peaceful, rare instances of aberrant behavior can occur in individual specimens.