So what have we learned so far?
Keep in mind my tank contains 5 Salminus Franciscanus only with no other fish.
Are they aggressive?
Yes but not all the time. There are mean and friendly days. If chasing and burst of scale loss stresses you out, then this is not the fish for you. Few members...correction....many members have experienced major damage and lost of fish from dorados. I think keeping larger numbers of them help spread the aggression.
How demanding are they?
Not demanding at all. They eat a lot so I stick with pellets to keep good water quality. WC once a week is fine. Never had open wounds or cloudy eyes. Very few torn fins or tail. Heals very quickly. Never medicated or salted.
Appearance?
As they get larger, more color appears. Fins and cheek turn yellow (golden) and some red on the tail and anal fin. They are very silvery under the right angle of light. Otherwise, they may appear dull and grey.
Teeth
These guys have a lot! They can crunch freshly dropped massivore pellets into bits. Sometimes you can see the pellet stuck on their front teeth because the teeth sunk in so much.
Tank
The smaller less aggressive guys do like to hide behind drift wood. However, they are fast swimmers and do run into them so sharp small branches may cause damage.
They do like current. I run about 10X turn over rate. 5 dorados in a 225g appears to be doable considering it has only been a year. Of course, if you can provide a larger tank it would be better but things to consider is will a larger tank promote more territorial aggression and knocking themselves out or damaging their snouts due to full speed darting.