Behavior Compatibility Determinant
Species Behavior
All aquarium occupants will to some degree or another have behavioral attributes. These attributes are generally instinctual in nature and not learned. However, some behaviors can be learned and often build upon an occupant’s instinctual behaviors. So, a fish that is instinctually predisposed to reclusivity may at times exhibit schooling behavior when a predator is present. There is safety in numbers.
Behavior can also change or be muted due to environmental constraints. A Loach’s instinctual behavior is to rummage through the bottom sand for food. If the aquarium has no sand the behavior of the Loach will change to just prowling along the aquarium floor for food scraps, not indulging in any burrowing behavior.
Age is also a behavioral determinant. The frye of fish, or young fish in general, do not exhibit the behaviors of mature adults. As a fish matures instinctual behaviors that are species specific will become increasingly evident.
With the many variations of behavior among fish, how does one map the behavior of one species against another to determine compatibility. A useful tool in this process is the behavior quadrant.
The behavior quadrant has four behavior elements positioned across from their opposite attribute. There is an implied scale from the center of the diagram to the outer side for each attribute. The center representing no presented behavior for an attribute,and the outer edge indicating a strong presentation of the behavioral attribute.
There is a lighter circle that runs through each attribute area representing what would be a normal presentation of a behavior attribute for an aquarium occupant. This is the normalcy curve and represents a normal behaving occupant.
The behavioral area has two groups of elements which oppose one another. The two groups are Aggressive:Calm, and Social (schooling):Reclusive(hiding). All occupants have these attributes.
The behavioral elements are positioned in accordance with opposition plotting. To use the chart the aquarist would plot an existing occupant’s aggressivity using the vertical axis. The occupant is either calm or aggressive. The plot would be located within the circle unless the occupant is unusually aggressive or unusually clam. In these instances the plot made by the aquarist would be outside the normalcy circle.
The aquarist would then plot the social nature of the occupant as either very social or very reclusive. Using the normalcy circle as a guide the plot would be on or within the circle.
To determine compatibility, the aquarist would then plot a potential new occupant to see if they exist on an opposing side of the quadrant element on the circle for the opposing element. The opposing side would indicate the new occupant will not interfere with an existing occupant.
The general rule for using the behavioral quadrant is to look for species that will take a place in the quadrant that is opposite to the other species in the aquarium.
As an example Neon Tetras are schooling fish that are social and enjoy swimming among plants. These fish would be well paired with Loaches who enjoy a reclusive life hidden in cave-like structures.
The loach would be marked in the red quadrant on the circle between the CALM and the RECLUSIVE lebels. The Neon Tetra would be marked in the green quadrant between the SOCIAL and CALM labels on the circle. So, these two fish would share the attribute of CALM and push into the two opposing areas of SOCIAL and RECLUSIVE.
Based on the behavior quadrant these two fish would be behaviorally compatible and could share the same aquarium.
If another occupant is desired, that occupant could be in the upper half of the behavioral quadrant and be fully compatible with the existing occupants of the aquarium.
Keep in mind that not all fish behave as they are supposed to from an instinctual perspective. Whenever introducing new fish be certain to do so when there is sufficient time to observe interactions between the new addition and other residents.
Bringing it all together
In the aquarium biome, compatibility is largely comprised of four areas. They are: Food types, Water chemistry, Species behavior, and Environmental. The closer there is alignment in these areas and their sub-elements, the greater the compatibility potential. Many aquatic occupants will overlap in these areas, or not be specific to a particular element in an area..