Can I keep a group of Common clownfish together?


Is it possible to keep clownfish in social groups in the marine aquarium? Matt Pedersen advises.

In the wild, many clownfish live in social groups of a dominant female, a male, and one or more subordinate sexually immature male juveniles. Social pressure keeps the younger ones, not part of the pair, from maturing. They patiently wait their turn.

Images of clownfish in the wild reveal many species in groups, including Saddlebacks (A. polymnus), Common (A. ocellaris), Percula (A. percula), Black-footed (A. nigripes), Clark’s (A. clarkii), Pink skunk (A. perideriaon), and, I’m sure, others.  

You may find big colonies of clownfish among large aggregations of anemones, with multiple pairs sharing adjacent spaces. However, I would never expect a group of a certain species to work, most notably the Maroon clown (Premnas biaculeatus).

Replicating the ‘pair plus’ social group in captivity doesn’t always work, but I’ve seen it work with ocellaris and clarkii, as well as having seen a massive group of Pink skunk (Amphiprion perideriaon) at Atlantis Marine World in Long Island, USA.

That doesn’t mean it will always work with these species. There is definite merit in adding all the fish at the same time as juveniles. If I tried adding a juvenile percula or ocellaris to a tank with a spawning pair, though, it would quickly killed.  

Starting with juveniles all at the same time has risks and in more aggressive species may fail to work. I have a small isolated group of five black ocellaris (Amphiprion ocellaris ‘Darwin’) which are all siblings — the larger two being hatched a batch earlier. Even at three months, social pressure has created a runt that takes the brunt of aggression, so it hides, only showing up to feed.

I suspect that if I removed this fish the next one would suffer, and so forth, ultimately leaving me with just a pair.

In nature, clownfish living in groups will breed. In captivity it's generally felt that if you have more than two in a group breeding will be delayed because the fish will spend more time determining social rank. You may reduce the chances of this happening by selecting a larger, medium and one or more small fish — all from a group of juveniles.  

Because size tends to correlate to social status and sexual function, judicious selection of fish may help reinforce the natural rankings each fish should occupy.  

These fish may or may not breed. Things may go well for a while, but then, as the dominant pair matures, they may attempt to drive off all other fish. This may result in deaths, or a second splinter group which then forms its own breeding pair.  

How all of this may occur depends on tank size, hosts and personalities. It is impossible to predict outcomes, so have spare tanks or breeder nets ready to isolate all extra fish if cohabitation doesn’t work!

Why have my clownfish suddenly stopped spawning?


If your clownfish have been breeding regularly and then suddenly stop, could it be a sign of ill health? Matt Pedersen looks at the possible reasons for them going on strike.

In the wild some clownfish species have breeding seasons and these are thought more likely in those in more temperate/subtropical locations. Wild spawning may also be tied to lunar rhythms.

In captivity it is not uncommon for clownfish to 'go on strike' and stop breeding. Sometimes they will resume, sometimes they won’t. There is no single answer, but here are some possible solutions.

Making a change or disrupting the broodstock aquarium can stop them in their tracks. Rearranging the tank’s décor could be enough. Adding new fish to the tank could also potentially throw them, especially if conflict results.  

Several clownfish varieties and species are typically thought of as unreliable spawners. Amphiprion ocellaris are generally not lumped in that category, but for people with fish like skunk species, including Amphiprion perideriaon, A. sandaracinos, A. nigripes and others, sporadic spawning is almost considered the norm!

As for 'seasonal' breeding, you may have inadvertently given them a cue to stop spawning. A drop in tank temperature could easily slow or stop them. All my tanks run cooler in the winter and spawning behaviour adjusts.

Shortening your lighting cycle could also be an environmental cue to stop spawning.

Other possibilities may include old age, although clownfish can live up to 30 years and I know of at least one 21-year-old pair of Tomato clownfish that still spawn routinely!

Look at their general health and condition. Low feeding levels may have caused them to stop to restore depleted reserves of nutrients required. Actual disease, parasite, virus or bacteria can also stop fish from breeding.

Any one factor could be your problem, so check and rectify. If this doesn’t work be patient, for in clownfish breeding time is the one thing we can’t substitute!

Why does my anemone keep walking round my tank?


Anemones can walk, and it's not unusual for them to wander round the tank. Nick Jones explains why.

Anemones can have demanding requirements as regards lighting, feeding, water flow, temperature and water quality. This may also sound necessary for many corals, but many stunning tanks full of SPS corals have struggling anemones.  

Anemones can walk. They find a position they feel comfortable in and bury their foot in the sand or attach to a rock. If conditions aren’t suitable in the reef tank they will wander, looking for a more favourable position. This can lead to neighbouring corals being stung or the animal getting  into an unprotected pump inlet and meet its doom.

If yours continues to move it’s because it can’t find a suitable location, the right amount of light or because water conditions aren’t exacting enough.

If your anemone doesn’t settle within a week or so, your tank may never be suitable and the best thing would be to pass it to another hobbyist whose tank is more to the animal’s liking.
Even established anemones will often move occasionally and poke out of different holes in the rocks. This isn’t something to worry about.

This article was first published in the Christmas 2009 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission. 

Can I keep corals under T8 lighting?


Yes you can, if you choose your corals carefully. Jake Adams has some suggestions.

There are many conditions under which corals can be kept under T8 fluorescent lighting. Keep non-photosynthetic corals such as Tubastrea (pictured above), Balanophyllia and Dendrophyllia species which require a weekly feeding of small meaty morsels.

It is still possible to keep all species of photosynthetic corals under T8 lighting as long as we know the limits of our lighting and have realistic expectations for the rate at which corals grow under reduced lighting.

In addition to generous water flow and feeding regularly, when trying to grow corals under T8 fluorescent lighting the aquarist should seek to optimise the performance and PAR output of his or her lamps.

Warmer coloured lamps will usually emit more PAR per watt, an efficient electronic ballast should be employed to maximise lamp output, every lamp should be coupled with a reflector and, where possible, the fluorescent lamps should be as close to the water surface as possible.

Although you may not be popular for handing out SPS frags left and right, there are still plenty of corals that will live and thrive, and sometimes even look better when put under normal output fluorescent lighting.

Most zoanthids, corallimorphs and leather corals should feel at home in a moderate light reef and many LPS such as disc corals, brain corals and even Acanthastrea lordhowensis should do really well under a few banks of T8 lights.

Although keeping corals in reef tanks lit exclusively with T8 fluorescents might seem out of place today, not that long ago the best reefs were lit exclusively with less efficient T12 fluorescent lights.

This article was first published in the Christmas 2009 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.