What does it mean when two adult angelfish swim in tight, fast circles around each other and seem to be locking their mouths together?
This behavior looks aggressive, but it is may actually be courting behavior. It means that you have a male and a female who have paired with each other. The next behavior to expect is that they will start to clean a surface to spawn on, such as a lift tube, a wide leaf of a plant, or a spawning slate. If the behavior persists, or if they seem to be aggressively attacking each other, you may have a male trying to defend his territory and his chosen mate from another male.
