watch for stress; find out if they are "schooling" fish; possibly separate them, or get a larger tank
Separate them as much as possible. If not possible, add more decorations and plants for more territories and feed them.
A water rocket should probably have three to four fins.
Dorsal fin, Flukes on the tail, and Pectoral fins on each side
The pectoral fins(located on each side) helps steer a fish during movement.
There are two sets of "paired" fins. The ones on each side of the fish behind the gills are the "Pectoral Fins" and the ones in front of the fishes vent on the underside of the fish are the "Ventral Fins". Sometimes these fins are wrongly refered to as "Pelvic Fins".
The pectoral fins(located on each side) helps steer a fish during movement.
get more of them so they'll even out there aggresive behavior on each other
Two fins - placed exactly opposite each other - will still allow the rocket to 'wobble'. Three (or more) fins equally spaced provide stability.
3in
The tail or caudal fin is attached to the spine. The others are attached to muscles.
Of course. They are not fast, but have little fins on each side.
Males have longer and fuller fins and females have shorter fins