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admin posted on March 07, 2006 18:15
It is a delight to see so many aquarists engaged in the keeping and study of reef creatures. In a relatively short period of time since the "birth" of popular reef aquarium keeping in the 1980's, the hobby has escaped the initial stigma of elitism and the challenge of growing the impossible to now seeing so many tens of thousands of hobbyists with thriving slices of the living reef growing in their own homes. Reef type aquariums run the gamut from nano-sized desktop adornments to swimming pool-sized captive reefs. And the collective interest of aquarists now extends beyond the wonderful pastime of ornamental use to endeavors of science and even revenue generation with some folks earning part- or full-time incomes from propagating corals. Whichever way you choose to celebrate the care of reef creatures in captivity, one thing is certain: reef tanks are excellent learning centers. We have progressed from the days of wondering how to keep some corals alive to now contemplating how best to control the excess growth of the same species.
And so, everyone participating in the keeping of corals will have to learn fundamental coral propagation techniques, if only to prune their growing display. In many ways, coral propagation is like gardening. There is a complex relationship between animals in the garden as revealed by small changes to any one aspect, which can easily influence another. For example, a piece of coral growing larger over time will change the dynamics of water flow around it and the light under it. Neighboring corals can be influenced significantly (usually for the worse) by the encroachment of others like this, yet the keeper often fails to realize just how fast or large the offender has grown without looking back at photographs, for example. In the typically crowded confines of home aquaria, this can quickly become a problem. Corals are mostly sessile organisms (they do not move around) and their very lives depend on water flow to carry food and nutrients to them and carry waste products away. Tip: reef aquariums need a minimum of 10-20 x turnover of water in the display - systems featuring small polyped stony corals like Acroporids may need twice as much! Photosynthetic corals, polyps and anemones are furthermore dependant on the quality and quantity of light that reaches them. Tip: provide at least 5 watts of daylight per gallon of water for a rough guide to illuminating reef corals properly. (do not count actinics or heavily blue colored bulbs). When so many systems are already modest or lacking in these parameters, any additional compromise as with overgrown, neighboring corals can harm other corals and lead to their demise in short time.
The animals that we call "corals" comprise a very wide range of organisms that one might say are actually more distantly related to each other than mice are to elephants! They come from tropical oceans spanning the globe and from niches with wildly varying physical parameters. This reality is one of the very things that makes the keeping of casual displays without themes or biotopic restrictions so difficult. The unplanned and random mix of corals that some aquarists make is not only unnatural, but harder to succeed with. There are several distinct reasons for this. The first and most obvious reason is that a low light animal like some mushroom anemones (corallimorphs) collected at sixty feet of depth cannot be expected to survive long term, or at least thrive, in the same 24" deep aquarium with an Acroporid (small polyped stony coral) collected in less than 10 feet of water. The extremes of water flow, temperature and lighting between these cnidarians' natural niches can be extraordinary. To make matters worse, we are beginning to learn more about the silent chemical warfare that corals, plants and algae conduct on each other (allelopathy). Preliminary observations suggest that the sensation of unnatural tankmates in "garden reef" displays can make some corals exude excessive chemical deterrents, which in the confines of a closed aquarium system contributes to their own demise as well over time. The energy spent to produce such chemicals is done so at the biological expense of other more desirable functions like reproduction, growth and perhaps overall vigor. Unfortunately, since the toxic effects of crowding corals and unnatural tankmates can take many months or even a couple years to take its toll, the weight of the problem is lost on many aquarists. We cannot forget though that a coral that survives two, three or even five years in captivity cannot be regarded as a success when the natural lifespan is many decades or potentially infinite (for some).
As a mentor and advisor to fellow hobbyists, I too must take into account some practical realities. Despite best intentions, it's true that most aquarists will not set up geographically natural or niche-specific biotope displays. Frankly, with science and "perfect-world" scenarios aside, I must admit that I too like the eclectic and often artistic displays assembled by some folks with random species in a mixed "garden reef" style. It's quite fine (wonderful indeed) to simply just want a hobby tank… so long as you can insure the overall health and welfare of the animals you take into your charge. And so, the question then becomes - how do we deal with the challenges of a mixed "garden reef" displays.
Tip: Faithful attention to water quality is one of the best ways to succeed in keeping mixed species coral tanks over time - invest in the best protein skimmer you can afford, conduct regular partial water changes, and use at least one kind of chemical filtration daily/full-time.
Water quality issues can be handled reliably with frequent water changes (small weekly exchanges are much better than large monthly events), aggressive protein skimming (tune your skimmer to produce near daily cups full of skimmate) and chemical filtration (using activated carbon full-time in small amounts changed weekly rather than 4x amounts changed monthly). From a husbandry point of view, corals should also be given enough minimum space between each other for safe growth and to temper aggression. Tip: place corals in the aquarium with a minimum distance of 6-10" between each other - more space is better. These basic guidelines will be a tremendous help for succeeding with mixed reef aquariums at large.
With this primer, I invite you to follow up reading the forthcoming parts of this series when we explore the specific and illustrated techniques for pruning and propagating hard & soft corals, polyps & corallimorphs and anemones.
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