BuffaloPolypteridae, those do in fact appear to be young Gymnogeophagus balzanii. As you can see, they're not quite as long and slender as Geos are. They tend to be more short and stocky with a taller forehead. They will fill out and get taller and more box-shaped as they age. Here is a picture of a juvenile balzanii for reference: http://www.aqua-fish.net/imgs/fish1/argentine-humphead-2.jpg
These fish tend to prefer a cool-down period each year as they come from more southern regions of South America (southern Brazil, Uruguay, etc.). You could probably keep them in an unheated tank throughout the winter.
These fish tend to prefer a cool-down period each year as they come from more southern regions of South America (southern Brazil, Uruguay, etc.). You could probably keep them in an unheated tank throughout the winter.