Other families possess both SPS and LPS genera, species. Here is Porites porites on the left, an SPS found in the Atlantic; and below right a Flower Pot Coral, genus Goniopora of the Indo-Pacific ; both of the family Poritidae.

Aquarists who are dive travelers realize that our tanks are artificial replacements in many ways; one big one: How they’re illuminated. Yes; it is bright near the equator; even underwater… at “high” noon. But the intensity of light is never constant and quickly drops off with the angle of the sun to the water’s surface, the depth of water, waves and more. Suffice it to state that it is rare indeed that the corals that are wild collected or aquacultured in situ in the ocean receive the amount of light energy we provide. Newly acquired specimens/colonies need to be gradually photo-adapted to new settings, placed in shadier settings, deeper in the water, or the light attenuated, possibly shaded itself to prevent over-driving photosynthesis. Here a new Acanthastrea is set on the bottom off to the side of overhead lighting.

Sudden or extended overheating may result in bleaching; the expulsion of endosymbiotic algae. Below, a Galaxea fascicularis was overheated from a combination of low tide and sun exposure in the upper Gulf of Aqaba, Red Sea. IF the skeleton remains intact and doesn’t become overgrown with algae, there is hope that tissue growth may return to the lost coralites.

There are as many types of chemical stressors as there are chemicals that occur in marine environments. Too little or too much of some is real trouble. In particular the mentality of many aquarists that “cleanliness is sterility”; utilizing high tech. equipment and chemical filtrants, along with scant feeding to produce a nutrient-limited system. Know then that all photosynthetic life requires the essential elements N, P, K… Unless you’re supplying Nitrogen, Phosphate and Potassium via foods; you are starving your corals if there is no measurable amount of these in your water. Too much is of course as bad as too little; you want some percent of Nitrate, and a few hundredths of a percent of soluble Phosphate. Below is an example of a coral lost and being overgrown by algae from eutrophication (too much nutrient) in Palau Redang, Malaysia.

Many other ways that Cnidarians contest with each other exist. There is over-shading for instance where one species grows out blocking light and possibly current from a colony below. Here in Bonaire a sea fan (Gorgonia ventalina) blocks light and current from the stony corals around its base.

Many folks misconstrue the world’s reefs to be idyllic, peaceful places where life is somehow living in co-dominant co-existence. This is not so; reef areas are battle grounds where life competes for space, food, reproduction… Below are two Montipora spp. fighting across a demilitarized zone for turf. Stressful? You bet.

Stinging, via mesenterial filaments and more is a type of “digestive dominance” where one or both parties lose. Providing plenty of space twixt colonies is important with very stinging species like Galaxeas (family Oculinidae), Euphylliids and Caryophylliids. A good foot (30 cm.) is not too much gap to provide. Below; a scrunched down stung Catalaphyllia.

Sudden to permanent polyp withdrawal from a living skeleton is cause of dire concern. Some agent is assuredly at work here; stinging perhaps crawling or worse, sampling the living tissue as food. Be alert and observant, consider moving the impacted specimen, possibly to another system or lighted refugium.
Below, a mal-affected Goniopora and a Euphyllia with tissue-removed skeletal area.

The easiest sign to spot early on is that your corals are simply not opening when they should. Most species extend their polyps by night in the wild… for feeding on nocturnal plankton and avoiding predation by day. Many do become reverse adapted due to being fed during lights on hours in captivity. Below, a fully extended Acanthophyllia in Raja Ampat, Indonesia.

Losers in allelopathogenic battles should be removed to another system if possible as soon as practical. Supplying them with a trebled dose of iodide-ate, a slightly lowered specific gravity (a thousandth or so) and adding a simple/hexose sugar at a level teaspoon per ten gallons may enable to speed recovery. The main, display system may benefit from  massive water change as well as application of granulated activated carbon and Polyfilter or equivalent in the filter, circulation path.

Some of the easier LPS Corals to keep.

Caulastrea species; Candy Cane corals.

Usually peaceful toward other Cnidarians; undemanding in terms of water flow and moderate lighting; easily placed at all levels in the aquarium.  Here’s a small C. furcata colony in Raja Ampat, Indo.

Cynarina species; Button Corals. These uber-fleshy polyps are amongst the safest LPS to stock; getting along with most all fishes and non-fish livestock. Moderate lighting and reduced current suits Cynarina well. Here’s a C. lacrymalis in S. Sulawesi, Indo.

Favites species; Pineapple corals. Aggressive species that need to be placed apart of other corals. Appreciate moderate light intensity and medium water flow. Several color varieties and species are offered from time to time in the trade. Here’s a F. halicora in Fiji.

Lobophyllia species; another group called Brain Corals. These corals can be aggressive toward other Stinging-Celled species, so you’ll want to allow several centimeters of space around their colonies. Lobo’s get along with moderate current and a range of light intensity. There are many color varieties to choose from; these L. hemprichii in Bali, Indo.

Nemenzophyllia turbida; Fox Coral. A peaceful species that can be placed anywhere in the aquarium; even on the substrate. Does fine with moderate lighting and current. This one in N. Sulawesi, Indo.

Plerogyra species; Bubble Coral. A group of species that are aggressive with other corals; needs a good 15 cm. (six inches) of no-man’s land about it to disallow it to reach out and touch someone with its stinging mesenterial filaments. Moderate light and current will do for Plerogyras. Here’s a typical colony of P. sinuosa off of Queensland, Australia.

Trachyphyllia geoffroyi; Brain Coral (one of a few species with this common name. A compact species that may be aggressive toward other corals (needs to have several inches empty space about it); placed on the bottom is best, amongst lower current and light intensity. This specimen in an aquarium in Sacramento, CA.

Turbinaria species; Pagoda et al. corals. A peaceful genera of Dendrophyllids; best kept on the bottom in medium current and subdued lighting. This small T. peltata in an aquarium.

Do know that with proper acclimation, introduction and growing together, many would-be incompatible corals can be grown together. The practice of isolation, quarantine of new specimens, the gradual mixing of water between the systems to introduce contenders, placement to allow for growth; and the all important element of patience is rewarded by all getting along; as these two Euphyllias here in captivity.

Examples of overt stress in corals: Tissue loss; along with bleaching and not opening polyps are first observable evidence of stress. Below a Cynarina lacrymalis is showing its septal teeth as it has withdrawn and lost flesh over the calcareous skeleton. Heron Island, Australia. Compare this with a full-fleshed robust specimen in the Red Sea.