When you maintain a reef tank, you must understand that corals will compete for your tanks resources. The corals compete for resources in two ways: through physical contact with other corals, or through chemical warfare between the different types of corals in the reef tank. If the corals engage in chemical warfare or physical contact with other corals in the tank, the bleaching or recession of those corals can occur.
Therefore, it is necessary for the reef tank owner to understand how each group of corals defend itself from other corals in order to maintain each species of coral in healthy conditions in the reef tank. Within the reef tank, there are three main categories of corals, each with different requirements for the reef tank. Small polyp stony (SPS) corals requires bright lights to illuminate the polyps, require strong water movements, yet are very sensitive to chemical interaction from other corals in the reef tank.
How to Keep Corals from Fighting in a Reef Tank
Large polyp stony (LPS) corals require both moderate levels of light and water movement, but many of these species have sweeper tentacles that can damage other corals in the reef tank if the reef tank owner does not account for this when establishing the reef tank. Soft corals are forgiving of fluctuations in the light and movement requirements of the reef tank, but often release chemical into the tank that slow the growth of stony corals. Placing these three groups of corals into the reef tank without carefully considering their requirements can create problem for the reef tank and it’s inhabitants.
A compatibility matrix can assist in the establishment of a reef tank with various types of corals. A compatibility matrix can indicate which coral species are compatible with other reef tank inhabitants through information about the requirements of each species of coral, as well as any threat that certain corals pose to other corals. For instance, acropora and montipora corals are often compatible with each other because each of these coral types have similar requirements for the reef tank, and do not attack other corals of any type.
However, leather corals and acropora corals are not often compatible with each other due to the terpenes that leather corals often release, which can stress the acropora corals, regardless of whether the corals of either type touch each other. Therefore, by using a compatibility matrix, reef tank owners can ensure that the corals that are added to their reef tanks will coexist with other corals in that tank. Another factor to consider for compatibility between the corals in the reef tank are the aggression levels of the corals.
Aggression levels can be either physical or chemical. For instance, torch corals are often considered to be highly aggressive due to the sweeper tentacles that these corals use to attack other corals in their tank. Other corals, such as zoanthids, is also highly aggressive, but use a chemical toxin called palytoxin to attack their neighboring corals.
Reef tank owners can use the ranking system of aggression levels of each type of coral to ensure that each reef tank contains only the corals that is suitable for that particular tank. Using the information gathered from the compatibility matrix, as well as information about aggression levels of the corals, reef tank owners can establish an effective placement strategy for the corals in their reef tanks. For instance, reef tank owners should place SPS corals in the upper third of the reef tank, as these corals require the strongest lighting and water movement in the reef tank.
Other corals, like LPS species, should be placed in the middle third of the reef tank, but only in areas where there is open rock to prevent the sweeper tentacles of those corals from attacking other corals in the reef tank. Soft corals should be placed in the lower portion of the reef tank, or on the sand bed of the reef tank, as these corals will not attack other corals in the reef tank, but other corals can avoid their chemical output if they are placed in these lower areas of the reef tank. Anemones should be placed in another reef tank entirely, or behind a divider in the reef tank, to avoid their wandering behavior and their potential to destroy other types of corals in the reef tank.
Owing to the knowledge of the chemical output of some types of corals, reef tank owners can use activated carbon to remove the chemical threats from the reef tank. Using activated carbon helps to remove the allelopathic chemicals that corals like soft corals release, for example. While water changes are also recommended for reef tanks, the chemicals will not be removed from the water in the reef tank as effectively as using activated carbon.
Therefore, although the goal is not to remove the defense mechanisms of any type of coral, reef tank owners can use activated carbon to prevent those defenses from overwhelming the reef tank. The chemical and physical parameters of the reef tank can affect the ability of the corals in that reef tank to tolerate other corals of the tank. For instance, SPS corals require stable levels of alkalinity and calcium in the reef tank, as deviations from these requirements can lead to stress for the SPS corals.
If SPS corals are stressed as a result of unstable water parameters, those corals are more susceptible to being attacked by other corals in the tank. In contrast, soft corals are more tolerant of fluctuations in the chemical parameters of the reef tank. Soft corals can tolerate higher levels of nitrates, for instance, which makes them more likely to thrive in tanks where other types of corals may struggle to survive.
By maintaining proper chemical and physical parameters for the corals in the reef tank, reef tank owners can minimize the stress that each of the corals experience, improving the survival chances of the corals when they encounter other aggressive corals of the reef tank. In addition to the information about compatibility, aggression levels, and placement strategies for the corals in a reef tank, there is some beginner corals that can be purchased and added to those tanks to allow reef tank owners to learn about the compatibility of corals in their tank. Many beginner corals are less likely to cause losses of expensive reef tank corals if they are placed into the reef tank incorrectly.
Green star polyps and pulsing xenia species are two types of beginner corals that exhibit rapid growth, and have a tolerance for various conditions in the reef tank. Duncan corals are another type of coral that are suitable for beginning reef tank owners to purchase for their reef tanks. Duncan corals are an LPS coral that is not aggressive like torch or hammer corals.
Therefore, using these types of beginning corals, reef tank owners can observe the growth of the corals in response to various lighting and water movement settings of the reef tank prior to introducing other, more aggressive corals into that tank. The most important skill for reef tank owners is the ability to recognize the patterns of the corals that must be avoided. Reef tank owners must be able to recognize both the presence of chemicals released by the corals from the reef tank, and the ability of the corals to physically attack other corals in the reef tank.
By gaining experience in establishing reef tanks, reef tank owners will develop an understanding of these different types of threats to corals in reef tanks. When reef tank owners understand these threats and recognized each of the patterns of chemical or physical threats from each type of coral, reef tank owner will be able to make decisions regarding the placement of those corals in the tank. Furthermore, the reef tank is an ecosystem, and every addition to that ecosystem has the potential to alter the balance of that ecosystem for all other organisms in that ecosystem.
