• Understanding Compatibility,
• Food types,
• Water chemistry,
• Species behavior,
• Environmental.

Water flow is an environmental area that is difficult to plot an aquarium occupant against.  An occupant has different tolerances for water flow speed and volume depending upon age, health, and current behavior.  To make the process slightly less difficult, it is assumed that the water flow area will represent a healthy occupant as an adult exhibiting normal behavior.

Using this criteria it is possible to determine what water flow conditions the potential occupant is most comfortable with.  Generally, larger occupants are tolerant of greater water flow with greater volumes of water.

The majority of potential occupants will exist somewhere within the circle representing an aquarium fish that can maneuver within the turbulence generated by aquarium equipment.

The majority of potential occupants will exist somewhere within the circle representing an aquarium fish that can maneuver within the turbulence generated by aquarium equipment.

A compatible fish in this element pair would be a fish that closely mimics the existing preference for water flow.  The reason for this stems from the difficulty involved in creating a fast moving stream next to a stagnant piece of water – in the same aquarium.  Not that it can’t be accomplished with enough tank area and proper aquarium technology to move water.  It would just be more involved and require good hydro engineering.

Water flow is plotted against the cave dweller/open water elements.  An aquarium fish typically exists in an aquatic environment that provides for isolation and protection or open water swimming.  The isolationist rarely emerges from their protective cave.  The exceptions would be for feeding, mating, or defending.

The polar opposite to the protective cave is the open water swimmer.  Some fish prefer not to be caught in a cave and are more inclined to swim in the open area of the aquarium.

Many aquarium occupants find themselves somewhere within the circle on these elements.  A potential compatible occupant to an existing fish population would be one that prefers the polar opposite of the existing population. As an example if the aquarist has a loach that prefers to be hidden, the aquarist should be looking for a fish that prefers to open swim as a compatible fish.

Environment 2 expands upon Environment 1 by introducing Vegetation and Illumination element pairs.

The Vegetation element represents a range of aquatic fauna from sparsely placed plants to thick forests of vegetation that can be difficult to see through.  Some aquarium occupants requires thick fauna to hide in and to forage for food.  Others prefer environments more easily navigated with unobstructed views.

Generally, most occupants fall somewhere in the middle.  There are exceptions where some fish require hiding areas and tall grasses on which to deposit eggs.  This type of egg-laying behavior requires floor grass for breeding.

For compatibility purposes it is possible to have polar opposites in the same aquarium for this element.  If the aquarium is sufficiently large, having areas of dense vegetation can satisfy those fish needing this type of fauna.

Plotted against Vegetation is Illumination.  Illumination is a somewhat complicated element to navigate when it comes to compatibility.

The Illumination element scale is between 16 hours and 8 hours of illumination.  This is because most aquarium occupants come from aquatic regions that can vary between 16 and 8 hours of daylight.

This is not to say an aquarist couldn’t create a biome mimicking the northern hemisphere and southern hemisphere supporting lighting requirements consistent with the sunlight phenomenon know as the “midnight sun”.

The intensity of light should be appropriate for the types of fish and plants in the aquarium. Some fish species come from habitats with bright, direct sunlight, while others are adapted to more shaded conditions.

Consider the following factors when determining light intensity and duration:

Low-Light Species: Fish species that originate from shaded environments or waters with dense aquatic vegetation may not require high-intensity lighting. Low to moderate lighting is often sufficient for these fish.

High-Light Species: Certain species, especially those from clear, well-lit waters, may benefit from higher-intensity lighting. Brighter lighting can enhance the coloration and activity levels of these fish.

Plants: If you have live aquarium plants, their lighting requirements should be taken into account. Most aquatic plants require moderate to high-intensity lighting for photosynthesis and growth.

Color Spectrum: The color spectrum of the light can affect the appearance and behavior of fish. While fish can see a broader range of colors than humans, a white or daylight spectrum is generally recommended for providing a natural look and promoting healthy plant growth. Some aquarists use lighting with a slight blue or red spectrum to enhance the colors of certain fish species.

Vegetation and decor will act to buffer incompatibilities among occupants with varying illumination requirements.  Occupants that require higher amounts of illumination will not be wandering about the vegetation where the intensity of illumination would be less.  Occupants requiring less illumination will not be wandering away from the protective vegetation where illumination would be greater.

Compatibility in the illumination area among occupants will be dependent upon hiding spaces.  Without hiding spaces the graphing of compatible fish species will be the same among all occupants.  Compatibility among occupants in a mixed vegetation aquarium, where there are hiding places, will be best if there are both high and low intensity tolerant occupants. In this situation the compatible occupants would lean towards each polar side and not be clumped 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.