Sometimes Corals Need Help


Out on the wild reefs corals are obviously left to their own devices. A constant battle is fought for dominance and space with individual struggles sometimes lasting for years. Some corals are much more aggressive than others but all seem to find their place.

In the reef aquarium the potential for conflict remains. If the aquarist has done his/her job with research and advice then this potential is reduced. Corals that are unrelated are not permitted to touch and all corals are given expansion space. They are also positioned according to their need for light and seawater flow.

All things being equal the reef aquarium will be beautiful but despite the aquarist’s care troubles could still occur because corals grow, some more quickly than others. This could cause interference with seawater flow or light and action has to be taken to correct this, this usually being a reduction in coral size by careful trimming. The upside of this is that the coral that has been cut will recover and there is another coral, the cut portion, which is now a new coral ready for growth. If there isn’t enough space in the reef aquarium, then another aquarist or a dealer is the answer.

It can be that the problem isn’t to do with overgrowth at all, but coral aggression because of a demand for territory. This could be seen by the aquarist as whitened ends to one coral while a neighbour is seen to be touching. As already stated some corals are more aggressive than others and the weaker usually has the discoloured ends. All coral struggles are not seen like this as for example if two much less aggressive corals are fighting then any discolouration could be completely missing.

The heading photo shows a coral that had grown a bit too large, it’s the leather coral (Sarcophyton sp) at centre a little to the right. The coral had grown out of proportion and was overshadowing others. The answer in a case like this is simple, some sharp scissors and the head was cut off. Enough ‘stalk’ was left attached and in a very short time new polyps were appearing. Just below this coral can be seen very young specimens of the same kind.


The photo above shows mainly green star polyps (Pachyclavularia sp) which spread on a purple mat. They are not considered aggressive and had given way to button polyps (Zoanthid sp), again not considered very aggressive, which had caused the star polyps to recede in a half circle. The button polyps were completely removed from the rock – one remaining can be seen near the left hand side centre of the photo. As a result the star polyps are expanding back onto the cleared rock space.

Sometimes coral expansion can just be too much for the space available or the desire of the aquarist as it ‘misadjusts the picture’. In this case it needs the coral in question reducing in area. The final photo shows a generally bare rock which was inhabited by several mushroom corals (Rhodactis sp). These were removed one by one leaving a smaller colony (not shown) intact. There is one mushroom to be seen which is at the bottom right corner of the photo. These corals were hard to remove because of their ability to retract very quickly, their slimy surface and their incredible regeneration ability – leave a bit in place and hey, another mushroom. On this rock has been ‘planted’ a very small colony of star polyps which it is hoped will cover the rock in time.

So the reef aquarist has much to look out for, not only the quality of seawater and lighting but the actions of the corals themselves. Coral territorial expansion could take place fairly quickly over a period of months or it could be years, so the two words so often used are here again – observation and patience.

  1. This a great informative piece,it is great to read these as it all is a learning thing balancing the marine and coral requirements,,,keep up the great work,regards kathy

  2. Hello Kathy.
    Glad you liked the article come back often.

  3. Hi John,Do you or any other members know if you can use to much UV on your Marine Aquarium,Please let me know !!!

  4. Hello Kathy.
    You cannot use too much UV though you can use more than is needed. UV radiation is applied within a sealed tube and the radiation cannot escape. Seawater is passed in a thin flow through the tube in which is located a UV bulb. A UV bulb should never be looked at directly of course and should be switched on within its housing.
    How can too much UV than is needed be used? This can occur when too large a bulb is purchased. The net volume of seawater should be ascertained (it doesn’t need to be completely accurate) and a bulb unit chosen that is adequate for this gallonage – the manufacterer’s blurb should suggest what’s needed. To ensure the UV radiation is effective the seawater flow has to be correct so choose a pump that is recommended or is known to give the flow rate the manufacturer recommends.

  5. Hi John,Its me back again,I have a Blue Tang and he has just recently had a couple of white spots on him which are the White Spot problem,hence why I asked about the UV Light.I Took him out of the main Reef & Fish Aquarium and put him in the Quaratine tank with a small amount of copper in the water and he was great within 24 hrs,I left him in the tank for a week and he was great,put him back in the Main 6ft tank and within days he was back with white Spot.I have spoken to our aquarium shop here and they say look the other way and it will go away and I now have a 36 w UV Sterilizer on the tank.I am worried that my lge Emperor Angel my get it and he and I certianly do not want to loose any of my Fish.Thinking back on it do you think it could be stress as The Emperor has a go at the Tang if he sees him out and about,they were entered in to the tank at the same time about 18 Mths Ago but there seems to be a bit of agro there.The Angel does no hurt the tang but shoos him away if he comes near.

  6. Hello again. I’m sorry to read your problem.
    If you have seen just one or two spots then the white spot outbreak isn’t serious, but nevertheless needs immediate attention as you obviously realise. I’m alarmed at the advice that your aquarium shop gave you!
    A UV system is a positive addition to a marine system where fish are housed. However, the UV should not be relied upon to deal with any outbreak of disease as it is not definitely 100% effective – this is because it cannot be definite that all seawater and parasites will flow past the UV. Think of all the different areas in the aquarium where seawater flow is slow, where it changes direction etc. I repeat that, though not an absolute requirement, UV is positively helpful.
    Many aquarists make the error of returning an infected fish to the aquarium too quickly. The life cycle of white spot is that they are seen on the fish, the spots drop off, they divide (ie multilply), then they re-enter the seawater column looking for something to attach to, that is fish. When seen the spots could then be much more numerous and infect more fish- and so it goes on.
    As you have done the best way is to isolate the fish in quarantine. The quarantine tank need be barely furnished, with minimum sand and perhaps just a plant pot (seawater safe such as clay) for the fish to hide in. The reason why decorations are minimal is that the effective treatment for whitespot is copper which can be effected by sand etc. It’s necessary to know the net gallonage of the quarantine tank reasonably accurately. Obtain a copper treatment and dose according to the manufacturer’s instructions. With respect “a small amount of copper in the water” won’t do, it’s necessary to maintain the required amount for the period specified at least, this is often two weeks or more. The extended period is to ensure that the white spot go through their cycle and are properly killed. The only time they can be properly dealt with is when they are in the seawater column looking for a host fish – hence the copper. (Do not increase the copper dose over the recommended level.) It’s really best to have a copper test kit which will show the amount of copper dosed.
    Remember that copper is dangerous to corals so do not move coppered seawater to the reef display aquarium. In the same way, do not use sand or rocks that have been in the presence of copper.
    When a fish is moved to quarantine, this isn’t a guarantee that the white spot is not present in the display aquarium as the devils could be off the fish but dividing, they could then infect other fish in the display aquarium. If so, the other fish should be moved to quarantine and the copper treatment continued for the recommended period from the point that the last fish moved in. Any infection left in the display aquarium should clear as there aren’t any fish to infect.
    The simple act of moving a fish to quarantine and back causes stress, so it should be done calmly and gently.
    When in the display aquarium and healthy all fish ‘argue’ from time to time. This is to establish a pecking order and sometimes territorial rights. The fish should generally be compatible of course. Stress could occur if fish have nowhere to hide at night – on the reef this means death and the instinct remains in captivity. It’s important that all the fish have somewhere to hide in the rockwork to give them security.

  7. Thanks John.It would seem that I am doing the right thing as the fish have lots and lots of rock hiding places.It makes catching them very hard as I do not want to disturb the Corals which are going great guns.I will just have to keep plodding along.Many thanks for all your hepl.regards Kathy

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