Coral Competition

Signs of Coral Competition

• "Wilting" coral polyps.
• Appearance of skeletons on existing corals.
• Formation of sweeper and/or marginal tentacles.
• Corals redirecting growth patterns.
• Cessation of coral growth.
• Dead or dying fish.

Marine Invertebrate Toxicity % Toxic % Nontoxic Gorgonians 100 0 Holothurians 100 0 Soft Corals 88 12 Sponges (exposed type) 60 40 Echinoderms 50 50 Tunicates 0 100 (Bakus, 1981)

So, are you limited to putting only non-toxic corals in an aquarium? If you look at the wide variety (including those which are considered toxic) of corals successfully maintained in aquariums today, the answer is obviously "no".

It has been found that corals have a tendency to want to coexist peacefully. It seems that there is a certain threshold that the antagonism (sending out test toxins) from other corals must exceed before a response is elicited. Also, corals which have coexisted in the same environment for a period of time tend to continue in the passive relationship until an outside influence (a new coral) or a new stress factor (sudden change in the environment) is presented.

Obviously, coral placement in an aquarium is extremely important. You certainly wouldn't want to pack Gorgonians and Holothurians close together in a tank. Fortunately (or unfortunately), there are no hard and fast rules for coral placement. Sometimes corals will "get along", sometimes they won't. It has been found that, as time passes, corals seem to learn to coexist, if the initial encounter is not fatal to either of them.

When placing corals in your tank, keep in mind that nematocysts can not swim upstream. In a closed system (your aquarium) the nematocysts will drift around in the current until they are either removed (filtered out), or land on and stick to something. Since the highest impact area from the free floating discharged toxins will be directly down stream from the offending coral, if a singular source of water current is used in the aquarium, the culprit should be fairly easy to identify in the case of detected damage to corals.

If a coral in an aquarium starts to cause damage, there are four basic options:

1. Move either the offending coral or the "victim" coral to another location in the aquarium.
2. Remove the coral from the tank.
3. Reduce or eliminate water movement in the tank (localizes damage).
4. Ride the event out, hoping for an acceptable outcome.

If options #3 or #4 are chosen, a good carbon filtration system will help reduce collateral damage in a tank.

In the end, the good news is that keeping a wide variety of beautiful corals in your aquarium can be done successfully. To see how other aquarists have accomplished this feat, visit the Reef Tanks Photo Gallery and note the combinations and placements of corals.

Coral Competition - Turf Wars in Coral Reef Tanks
Coral Competition - Coral Toxicity To Fish
Coral Competition - Signs of Coral Competition