There it is! Wait, it's a different one! There it is again! Now it's gone! What are they doing, where did your beautiful, brightly colored cichlid fish go and why do they keep moving around the rocks in your aquarium?
In a sense, territoriality is the basis for every reason that cichlid fish move around the rocks in your fish tank (or, for that matter, why they also move the rocks around in your fish tank). Cichlids are known for being territorial and aggressive. They choose certain areas of their tank as their own and defend them vigorously. They like areas with clear visual boundaries, such as the spaces between rocks, and if they do not feel that there is a suitable area, they'll make one by digging, pushing rocks and tearing plants out of the substrate.
Cichlids often move around the rocks in a fish tank because they are trying to hide from the bigger, meaner fish that are chasing them. Male cichlids stake out territories, and once they have their favorite area they will chase all other fish away. Unfortunately, fish tanks don't provide many places to hide. You can prevent this chasing behavior from becoming dangerous by arranging your rocks so that there are many places where fish can get out of each other's line of sight.
If you are not a fish it can be difficult to tell whether cichlid fish are fighting or fomenting romance. Both territorial defense and courtship involve chasing and visual displays and both can turn violent if the subordinate fish (a smaller male or a female) is noncooperative. Your cichlids may be moving around the rocks because they are courting each other, or because they are fighting over prospective courtship partners.
The ultimate goal of all of this territorial defense and courtship is to provide a safe space to rear young. Unlike most fish, cichlids care for their young both as eggs and after hatching. Your cichlids may be moving around the rocks (and also moving rocks around) to find, build and defend suitable nest sites, and then to keep other fish away from their babies. Whatever the initial reason for all of the moving and chasing, baby cichlids are meant to be the end result. Help by making sure that you have plenty of space for all fish to get out of sight of dominant fish and to escape aggression and for each fish or courting pair to build and defend a territory and nest.
- blue cichlid image by Earl Robbins from Fotolia.com