Marine starter fish to avoid


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For many, the lure of the marine hobby is irresistible, but before you jump in at the deep end, Dave Wolfenden explains why certain fish should be avoided by newbies.

Having a little slice of the coral reef at home is brilliant — when it’s going well. What’s not to like about the seemingly endless array of attractive fish and invertebrates available? However, many newcomers to the hobby learn the hard way, plumping for fish that, for various reasons, fail to thrive or just don’t survive.

In fact, a good proportion of beginners are so frustrated with these initial experiences that they give up, never to return to fishkeeping. And that’s kind of sad. So, what makes some fish more of a challenge than others, and what fish should be avoided?

Finicky feeders

Some species are extremely difficult to feed in captivity. This could be because they simply fail to adapt to captive diets, are notorious for going on hunger strike as soon as they’re placed in the aquarium or have such specific requirements (such as obligate corallivores — species which exclusively munch on coral polyps) that it’s impossible in practical terms to sustain them. Notoriously falling into this category are several species of butterflyfish, which have a wild diet solely consisting of SPS (Small Polyp Stony) corals.

Meeting their feeding requirements in captivity is extremely difficult, as it obviously relies on meeting the challenge of supplying sufficient corals for them. Research is the key here, and never buy a butterfly on a whim without being absolutely certain of its feeding habits.

The list of obligate corallivores is long, but luckily, responsible retailers will seldom stock them, and in any case, plenty of butterflies are suitable for the large, mature FOWLR (fish only with live rock) system. Butterflies aren’t the easiest of fish to keep, but species such as the Threadfin, Chaetodon auriga; Pearlscale, C. paucifasciatus, and Golden, C. semilarvatus, butterflies adapt well to captive diets and fare well if given good water quality and ample room.

Back in the day, cleaner wrasses of the genus Labroides were touted by some authors as being a virtual 'must have' for the marine aquarium. The thinking was that their habit of picking off parasites from client fish on the reef would reap benefits to the cleaner’s tank mates.

Sadly, we now know that cleaner wrasse generally don’t fare well in captivity, and as a beginner fish, they’re a no-no. Most systems can’t provide suitable numbers of client fish to sustain their needs (consider that one cleaner wrasse may be visited by many hundreds of clients in a single day, and you get the idea).  

Cleaner wrasses vary in their difficulty, with the stunning Hawaiian cleaner, L. phthirophagus, generally considered virtually impossible to maintain in the long-term. The only species that can be remotely recommended is the Bluestreak cleaner, L. dimidiatus, and this is not one for newcomers; it requires a large system, plenty of tank mates and ample supplementary food, as well as perfect water quality. Bear in mind that the obsessive-compulsive behaviour of cleaner wrasses can also be annoying to tank mates, and their constant pecking can damage the skin of many clients in the aquarium.

Fortunately, there are alternatives to cleaner wrasse that are much less challenging. Fish-wise, the cleaner gobies, Elacatinus spp., from the Caribbean are hardy, adaptable and peaceful — just make sure they’re kept with non-aggressive tank mates. And there’s always cleaner shrimp such as the Ambon cleaner, Lysmata amboinensis, which are similarly happy to either clean fish or accept any manner of prepared foods.

The ever-popular mandarins, Synchiropus splendidus and S. picturatus, have that undeniable 'grab factor', and it’s easy to see why, with their outrageous psychedelic markings. Mandarins are best avoided as first fish, however. To thrive, they require a constant diet of benthic copepods, something a newly-established system usually fails to provide. It is possible to add copepod cultures to the aquarium and/or train the mandarins to accept frozen feeds, although these approaches can be expensive and time-consuming. Starved individuals wane away

over weeks or months, assuming a grim look.

Dodge disease

Some fish are more prone to disease than others. Disease is, of course, a risk with keeping any fish, and the use of adequate quarantine facilities is a must to prevent parasites and other nasties from entering the aquarium. However, there are several species commonly found in the hobby that represent a high risk of introducing disease, and why give yourself the stress and hassle of having to carry out treatments if they do occur?

Believe me, treating an outbreak of Whitespot, Cryptocaryon, or Velvet, Amyloodinium, in any aquarium is not fun. It can happen with any fish, but avoiding some species lessens the risk. Plenty of folks (me included, unfortunately) have learned the hard way, so you don’t have to.

The 'usual suspects' for parasitic disease include various tangs — the Regal, Paracanthurus hepatus, for example, and I always wince when I see a Powder blue, Acanthurus leucosternon, in any dealers’ holding tanks; I just see these fish as a ticking white spot time bomb. I don’t know exactly why, but they appear to suffer from parasitic diseases alarmingly often. They’re by no means impossible to keep, but as a beginner, I’d be reluctant to take one on. Opt instead for one of the more robust Zebrasoma species. Caution should also be advised with clownfish, as parasitic diseases such as Brooklynella are often a problem; quarantining new stock is a must.

Avert aggression

An additional consideration for beginners is the temperament of the fish. The coral reef is a frantic environment, with often-fierce competition for space, and many fish have evolved aggressive behaviours to establish and maintain territory.

Many small species have pugnacious tendencies far out of proportion to their diminutive sizes, and, in fact, many of the most troublesome species are sold as beginner fish due to their hardy nature. Some of these fish may be quite bulletproof, but their constant squabbling and harassment of tank mates (and often each other) makes them less than appealing.

Take damsels, for example. These fish have plenty going for them in terms of outright ease of husbandry. They’re often small, which allegedly ticks the nano tank box. Not only that, they are able to cope with ammonia and nitrite spikes and can often tolerate parameters that will see many other fish rapidly shuffle off this mortal coil. As a result, they’re frequently added as the first stock in a newly-established system, but this is a bad idea.

A little Humbug or Domino damsel (various Dascyllus species) or aptly-named Blue devil damsel, Chrysiptera cyanea, might look like butter wouldn’t melt, but allow one to establish its territory and further additions of stock could be in a whole world of hurt.

Similarly, Tomato clowns, Amphiprion frenatus, themselves members of the damsel family, are very appealing, with great looks, and they’re hardy too. Small ones can be little charmers, but as they grow, they can play havoc with the rest of their tank mates as well as conspecifics in some cases.

Not all damsels are such brutes, however. While not exactly angelic, the Yellow tail and Azure damsels, Chrysiptera parasema and C. hemicyanea respectively, are, on the whole, much better behaved and a better choice for the newcomer. In terms of clownfish, Common clowns, Amphiprion ocellaris, are generally quite docile, and at a push, I’d recommend the timid Orange skunk clownfish, A. sandaracinos, providing optimal water quality and a host anemone are provided. Quarantine all clowns upon purchase, and buy captive bred specimens whenever possible.

Size up your species

Some species simply get too large for the home, and with the rise in popularity of the nano aquarium (sub-100 l/22 gal or so systems), this will be a ‘big’ problem for some. Juveniles of many species on offer by retailers may be small and cute, but look after them and they can soon outgrow their aquarium. A good example is the Yellow boxfish, Ostracion cubicus, from the Indo-Pacific. Almost unbearably appealing, baby boxfish are often imported little more than a centimetre in length, and their bright yellow colouration lends them the appearance of a swimming piece of sweetcorn.

Unfortunately, adults mature to a drab mustard colour and can reach well over 30cm/12" in length!

A quick check of adult sizes on FishBase ( can save a whole lot of hassle in the long run. Incidentally, captive sizes tend to be a little smaller than those quoted on FishBase, but to be on the safe side, assume yours can get that large.

Five more to avoid

1. The Blue cheek sleeper goby, Valenciennea strigata comes from the Indo-Pacific and grows up to 17cm/7". It’s an attractive fish with a habit of burrowing in the sand, ingesting mouthfuls of substrate and extracting algal films and microfauna as food. Unfortunately, many slowly starve to death in newly set-up tanks due to a lack of food. They’re straightforward enough in mature aquaria, but don’t get one for a new system.

2. The ubiquitous Green chromis, Chromis viridis (which usually grows up to 7cm/3" in captivity), is one of the top ten marine fish in terms of numbers imported. These small Indo-Pacific fish are a real bread and butter species and continue to be popular. For my money, they’re not a great beginner’s fish for a couple of reasons. Firstly, despite their hardy reputation, they can be extremely sensitive and they tend not to transport well. Secondly, they’re quite boisterous, and while some folks have luck with maintaining them in nano aquariums, I’d be very wary of confining them in a small system.

3. The Harlequin sweetlips, Plectorhinchus chaetodonoides, is from the Indo-Pacific and is a species that is seen far too often in the trade. I’d urge anyone contemplating getting one to think if they can really maintain it. Sure enough, juveniles of a few centimetres in length are cute enough with their waddling movement and attractive brown and white markings. If you can get a juvenile sweetlips feeding and really doing well in the aquarium (and that’s often a big 'if', as these can be extremely poor at adapting to captivity), expect an adult to reach 50cm/20" long — maybe even more — and become a relatively drab colouration, nothing like its bizarre former self.

4. The Twin spot wrasse, Coris aygula, from the Indo-Pacific, is easy enough to keep — at least as a juvenile. It’s a hardy species and eats like food’s going out of fashion. Tiny ones are often imported and they’re lovely, with their orange and black markings and white body. As they age, however, Twin spots change and not for the better. Before long, that cute little wrasse that entertained you with its lively swimming will become a humpheaded, destructive lump of a fish capable of toppling rockwork and generally creating mayhem on a large scale. Oh, and did I mention they can reach over a metre in length?

5. The Copperband butterfly, Chelmon rostratus, from the Western Pacific, which grows up to 20cm/8", doesn’t fall into the obligate corallivore category, but they are still very challenging and not recommended as a first fish. This beautiful species feeds on small crustaceans, fanworms and other microfauna in the wild, as well as being partial to the odd polyp (with many aquarists employing them to deal with infestations of Aiptasia anemones). While some specimens appear to adapt well to captivity, accepting a variety of prepared foods, all too often these fish appear to last only a week or two before dying often for no apparent reason. On balance, these fish require expert care in terms of husbandry, and selecting a good specimen requires lots of experience.

Still want a mandarin?

The good news is that they’re perfectly possible to maintain in the right system. Wait until your reef is fully established (this can take up to a year or so in some cases) and consider additions of benthic copepods to boost populations prior to introducing the fish.

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