Fish eating other fish

[tommo_uk]

I was told that a Silver Dollar will eat any Tetra's if it can fit into its mouth. Is this true, even though they are from the same family?

 

[Purrbox]

This is true of many larger fish, though I don't know about Silver Dollars specifically. Fish usually only care about whether they can fit it in their mouth, and many fish of any size will eat their own fry.