SAIA, the Sustainable Aquarium Industry Association, the European organisation for everybody interested in an ethical and sustainable Marine Aquarium Trade and Industry, has published a list of unsuitable and unsustainable fish species.

This document can be freely downloaded from the SAIA website.

This is a consultation document and SAIA welcomes feedback and discussion from all aquarists regarding the listed species.

The primary objective of the list is to raise awareness for a responsible, ethical, and sustainable hobby and trade by considering the difficulties in keeping certain organisms alive in captivity. The list identifies species where there in no justification for their being traded in volume.

In the first instance, the aim is to raise awareness in the average hobbyists who bear the disappointment and cost of choosing an unsuitable species.

For the industry the list should serve as guideline on what to avoid when placing an order, with the exception of where the listed species is requested by a buyer with either proven record of being capable to keep such specimens or for the purpose of breeding or research. Such buyers are not the average hobbyists.

SAIA would like to point out that the number of species listed as unsuitable or unsustainable is represents a small proportion of what is traded, so no significant loss to business and economy would result from adhering to this list, nor does it restrict the hobby significantly in the variety of species on offer.

The majority of the species concerned are available only from the wild, and it has to be questioned why such species, which do not survive for long in captivity or are threatened with extinction, should be traded. The intent of the list of unsuitable & unsustainable species is not to totally ban the listed species from trade, but rather to raise awareness and hence decrease the demand for such species.

Before reading the list I would suggest first reading the criteria for inclusion, reproduced below from the SAIA website, to enable the reason for listing to be put into perspective.

Note: where a family or genus is listed, the criteria in question relates to all members of that family or genus.

Criteria for unsuitability:

• Diet: Require a specialized diet that is difficult to duplicate in captivity e.g. coral polyps, sponges, tunicates, etc.
• Habitat: Require a specialized habitat which is very difficult to simulate (e.g. deep sand bed, depths of more than 10 meters)
• Aggressive: Extremely aggressive, have large territories in the wild, and are unsuitable for community aquariums. Note: aggression in fish is not anger but is due to territorial behaviour.
• Size: Grow too large for home aquariums, may require 4000 litres or more. It is not enough to merely provide a tank where the organism is well covered with water, an adequate habitat appropriate to the species requirements should also be provided.
• Stress: Those species that are sensitive and stress easily, do not transport well, and are susceptible to parasites and disease. This classification also includes species that only seem to survive in an aquarium when kept in large shoals and those that are collected from deep water, often improperly.
• Potentially harmful: information on venomous/harmful species will be provided shortly.

Criteria for being unsustainable:

• Rarity:  If it is difficult to find a species in the wild this may be an indicator of rarity. The minimum criterion is data deficiency on stock status. The industry does not want to stand accused of collecting a species to extinction.
• Destructive collection methods: collection of these species might lead to destruction of the habitat e.g. cyanide/drug use.
• Stock Status: the species is threatened in its population by other activities e.g. by catch of food fishery, habitat loss.
• Source: species being readily available from culture/breeding should not be taken and offered from the wild.

Some species might hit several categories and criteria, some only one. Nevertheless, species marked as unsuitable or unsustainable should not be demanded by or sold to the average hobbyist.

The list is not exhaustive, it is a work in progress, currently only covering fish species, which will be updated and extended, over time.

If you have any comments regarding this list please contact SAIA directly through the SAIA website. If you have any queries regarding SAIA in the UK, please feel free to contact me.

Tim Hayes

Midland Reefs

©2010

SAIA

©2010

In this article I’m going to discuss a few commonly available species that are difficult, if not impossible, to maintain in captivity.

People often complain about the cost of the reef aquarium hobby, well one way you can save a little money is by only buying species that are within the capabilities of you and your reef system, avoiding those that are more difficult to maintain and, to be blunt about it, destined to die prematurely in captivity. Some more advanced reefkeepers may quibble with my views and there is always that exception to the rule, the aquarist who has managed to keep some impossible to maintain species for many years. That does not negate the fact that the vast majority of these species will die in the hands of less experienced reefkeepers.

Why Don’t These Species Thrive in the Aquarium?

Nutrition

In nearly every case, the problem is one of nutrition. The majority of the species listed below are heterotrophic, that is organisms that, unlike photosynthetic (or zooxanthellate) corals cannot manufacture their own food. This can be further broken down into the amount of food required by a particular organisms or whether there is a specialised feeding requirement.

Quantity.

It may be possible to maintain some heterotrophic species long-term if they are fed large quantities of planktonic food, phytoplankton and or zooplankton, but this has the downside of producing a polluted environment requiring an onerous amount of tank maintenance.

This mitigates against keeping these organisms with nutrient sensitive corals species.

Specialised Feeding Requirements.

This includes many factors: particle size, diets restricted to a single food source often a specific algae, sponge, or other invertebrate such as a coral species.

Specialised System Required.

In particular, this applies to jelly species; with one exception, all jelly species need to be kept suspended in the water column. This requires the use of a specially designed system known as a Kreisel, which imparts a circular flow to the system, keeping the jellies in suspension.

Short Life Span.

Many of the animals discussed in this article have a short life span, depending on species this can be as short as a few months up to a year, possibly two, as a maximum. Although some aquarists may accept keeping an animal with a short life span, the major problem here is that is almost impossible to tell how old these organisms are; you may find you’ve been fortunate enough to have purchased a juvenile but you’re just as likely to have bought a specimen on the verge of senescence.

Commonly Available Species to Avoid.

Porifera - Sponges

The majority of the decorative sponges do poorly in captivity, they are heterotrophic animals i.e. organisms that, unlike photosynthetic (or zooxanthellate corals) cannot manufacture their own food. The exceptions to this tend to be the autotrophic sponges coloured green, through blue, to purple, that contain symbiotic blue-green algae which can utilise light, contributing towards the sponge’s nutritional requirements much as in zooxanthellate corals.

Heterotrophic sponges however are filter feeders and are reliant on a combination of dissolved organics, bacteria, and phytoplankton. For their aquarium maintenance, I would suggest feeding with a quality live phytoplankton such as DT’s.

Many sponges produce toxins as a form of defence, hence limiting the number of animals that predate on them. Dead sponges can release these toxins to the detriment of soft corals.        On the whole it’s difficult to say which sponges are heterotrophic, which are autotrophic, which are toxic, etc as, with the exception of a handful of distinctive species, these are difficult animals to ID with any certainty. This also makes it difficult to make recommendations on placement, although many sponges will benefit from lower levels of light, there are also those which can be found in shallow water even though they have no photosynthesising symbiont.

A further factor in lack of success with sponges may be that of Silicate limitation owing to the widespread use of RO water in reef aquaria.

Cnideria

Hydrozoa.

Stylaster and Distichopora species. Common Name: Lace Corals

These hydrozoan corals don’t have as powerful a sting as their close relations, the Fire Corals, what they do have though is vivid colouration making them attractive to aquarists. Unfortunately, these azooxanthellate corals are very difficult to maintain owing to their dietary requirements of plankton and possibly nutrients absorbed directly from the water. The colours, blues, violet, pink, through to red are derived from foods rich in the caratanoid, astaxanthin, so perhaps CyclopEeze FreezerBar may be a useful addition to their diet. They are also adapted to strong current, which may also be a factor in their poor survival in the aquarium.

Scyphozoa

Cassiopaea species. Common Name: Upside-down Jellies. Aurelia species. Common Name: Moon Jellies.

Whereas Upside-down jellies can be accommodated in a conventional aquarium if attention is paid to their requirements, all other species of jelly need to be kept suspended in the water column.

Jellies have a complicated life cycle and none but the most advanced aquarists or public aquariums will have much success in raising these animals. Life span is dependent upon species and environment, can be from months up to a year in the wild. Note: Aurelia species are cold water, not tropical.

Pennatulacea

Cavernularia species. Common name: Sea Pens

In addition to being a heterotroph requiring targeted feeding of planktonic food, sea pens need a very deep substrate. These unusual and interesting soft corals dig their peduncle or “foot’ into the substrate as an anchor, this can be more than half the body length of the animal, depending on species, and considering that some species can grow to a height of 40 cms or more, we can be looking at a considerable depth of substrate, deeper than some aquaria.

Nephtheidae and Nidaliidae

Stereonephthya, Scleronephthya, Dendronephthya, Siphonogorgia species. Common name: Carnation Corals

Heterotrophic. These gorgeous, brightly coloured corals are difficult to accurately identify to genus, let alone species level. All require large amounts of food if they are to be kept alive for any length of time but all are destined to waste away over time

Poritidae

Goniopora species.

Sometime over the last couple of years a long-time US aquarium writer, I can’t remember whom, made an observation to the affect, “Back in the eighties, when corals led short lives in the aquarium, we used to feel that we’d done well when a specimen of Goniopora lasted as long as twelve months. Today we can keep most corals indefinitely, yet Goniopora still rarely survive for more than a year!”

Unfortunately, this species remains one of the corals imported in greatest quantities and one of the species least likely to last out a year.

Goniopora species contain zooxanthellae but even that is not enough for the coral to survive without wasting away. There is speculation that a large part of their food take up in the wild consists of a combination of phytoplankton and small particle zooplankton.

Caryophyllidae

Nemenzophyllia turbida. Common name: Fox Coral.

Another zooxanthellate coral that does poorly in the reef aquarium. Again, it is possible that like Goniopora it has a particular feeding requirement that cannot be easily accommodated in the aquarium, in this case the animal may be reliant on absorbing nutrients from the water.

Additionally there is concern about the restricted distribution of this coral; hence, sustainability of collection is in question

Dendrophylliidae

Tubastrea species. Common name: Sun Corals.

This is a heterotrophic or azooxanthellate coral, and is completely dependent on receiving sufficient zooplankton to survive. I have mixed feelings about this coral as, although it is azooxanthellate, it is also the species I’d recommend to any one interested in trying to maintain heterotrophic corals. I would categorise it as being the easiest non-photosynthetic coral to keep alive long-term but to do this requires real dedication to its care. The finest example of an aquarium featuring this species belongs to Swiss aquarist, Daniela Stettler; her dedication is such that she feeds each individual polyp with artemia every evening.

Platyhelminthes

Pseudoceros species. Common name, Flatworms

Gastropoda

Phylidiidae species, Hexabranchus species, Chromodoridea species. Common Name: Nudibranchs, Sea Slugs.

Both Flatworms and Nudibranchs are often difficult to identify. They share the two main limitations of diet and longevity. They may have very specific diets relying on one single species of algae or animal and these foodstuffs may not be present in the aquarium. Although some of these animals may have vivid colouration making them attractive to aquarists, they appear to have short life spans so, even if you were fortunate enough to have the appropriate diet available, you may be dealing with a species that lives for six months or less. Some species may also be toxic with the potential to pollute the tank when they die.

Bivalvia

Lima scabra. Common Name: Flame Scallops. Spondylus species. Common Name: Thorny Oysters.

Heterotrophic. Another couple of animals that require large amounts of food if they are to be kept alive for any significant length of time. Both species feed predominantly on phytoplankton although the addition of small particle size zooplankton such as rotifers may increase survival.

Flame scallops are short lived, maximum of three years, so given retailers preference for stocking bigger animals it may be that most of those in the trade are of an advanced age, explaining why they rarely survive for more than six months.

Cephalopods

Order Octopoda - Octopuses, and Order Sepiida - Cuttlefish

These highly intelligent molluscs have specialised requirements for housing. Nearly every public aquarium, livestock supplier, and retailer that has kept octopuses will have tales to tell of these Houdini’s of the deep. These animals are master escapologists, capable of squeezing through the smallest gap and there are many stories of mysterious fish losses that have eventually been traced back to an octopus leaving it’s tank at night for a takeaway meal, then returning to it’s own aquarium afterwards.

Octopus and cuttlefish have short lives, living for one year, possibly two at the most. It can be distressing seeing these fantastic animals fade into senescence towards the end of their life and knowing that there is nothing you can do to help them.

Echinodermata

Crinoidea Feather Stars and Ophiuroidea Basket Stars

These close relatives of the more familiar Sea Stars and Brittle Stars are filter feeders that rarely survive in captivity for any length of time. It is currently unknown whether this down to lack of food or selectivity of diet.

As they die there is a tendency for their arms to fragment, which can often be seen to continue moving after separation.

Holothuria

Pseudocolochirus species. Common name:  Sea Apple

Heterotrophic. A brightly coloured member of the holothurids this animal is highly toxic. If not fed sufficient quantities of food it will waste away and die, this frequently results in the death of any fishes in the aquarium as the powerful toxin, holurathin, is released.

The Exception to the Rule.

There are a couple of possible explanations for those reports of aquarists having managed to keep seemingly impossible to maintain species long-term, which may hold out some hope of being able to maintain some of the animals in the future.

Identification.

Given the difficulty in identifying many reef organisms accurately there is the possibility that these species may have been misidentified and that they have different requirements to the species in question. This includes the possibility that some look-alike species that do survive longer than usual in aquaria are undescribed species.

Origin.

The animal in question may have been collected from a different part of the reef to where it would normally be found, and has adapted to conditions differing from its usual habitat making it more suited to life in the aquarium. For example, it has been reported that crinoids living in plankton poor environments may have arms that are longer and more highly branched than those inhabiting plankton rich environments.

These animals collected from abnormal habitats along with their adaptation to the environment, may mean that we are seeing organisms in the process of evolving into new species.

Afterword.

Although I have highlighted a number of factors that may improve the chances of keeping many of the animals discussed for longer periods, I do want to emphasise that the overwhelming majority of the animals listed will die in the marine aquarium within a few months of introduction.

Glossary.

Azooxanthellate coral - a coral that does not have symbiotic zooxanthellae in its tissues.

Heterotroph - an organism that cannot manufacture its own food, and therefore requires external sources of energy.

Hydrozoa - a class within the phylum Cnidaria, contains five orders that include colonial forms with massive aragonite skeletons, fire corals and Lace Corals.

Tim Hayes

Midland Reefs

©2010

While starting to research unsuitable fishes for SAIA, I remembered this article from a couple of years back. Hopefully this should explain some of the rationale behind restricting the availability of certain species of fish. Personally I would not want to see the trade in these species banned, rather that availability should be restricted to:  those with the capacity to provide suitable accommodation - in the case of large species, advanced aquarists  - in the cases where it’s a matter of nutritional limitations.

Criteria for Unsuitability.

SAIA’s criteria for unsuitability include: size (organisms growing too big for the average hobbyist tank), feeding (specialist feeders), and sensitivity to transport conditions. We believe that as part of our goal of an ethical and sustainable marine aquarium trade that we can reduce the demand for unsuitable species by making information available to both the trade and the hobby. Below are a few further comments on some of the criteria for unsuitability.

Generation replacement time.

Many fishes have a slow generation replacement time; meaning collection for the aquarium trade can affect the sustainability of the breeding population.

Rarity in the wild.

Some very desirable species are comparatively rare in the wild.

Limited natural range.

A good example of course being the Banggai, a limited range implies a small population that can be easily over-exploited by the aquarium trade.

Method of capture.

Owing to their habitat there are fish species, which are difficult to capture, fishes such as dwarf angelfishes and mandarins come to mind. Cyanide is still in use, along with a number of other chemical agents that are used to knock out fishes to make collection easier.

Nutritional requirements.

If you can’t feed it, you can’t keep it!

Just because some retailer tells you, “No problem, it’ll eat anything” it doesn’t mean that they’re correct. Research fishes’ nutritional requirements, if you cannot accommodate a specialist feeder do not buy it thinking it’ll acclimate to aquarium food in time, it won’t, it’ll starve to death!

Size.

This is of particular importance in view of the public aquarium Big Fish Campaign, launched in 2006, which aims to educate aquarists about the potential sizes of fishes in the trade and point out that public aquaria cannot be relied upon to take care of poorly thought out purchases, when they outgrow home aquaria.

Remember, when you buy a fish it shouldn’t just be something to keep until it outgrows your system, you should be making a commitment to keep that fish for the length of its natural life, something that in many cases should be measured in decades not months!

On the subject of size, there is also the question of what size fish should be collected for the trade, this can affect the sustainability of the breeding population of a species. Size can also have an influence on how well a particular species survives the process of collection and transportation.

10 Marine Fishes You Shouldn’t Even Think About Buying.

Elasmobranches.

Elasmobranches, sharks and rays, should remain the provenance of public aquaria. The only exception to this rule is if you can provide facilities similar to those of a public aquarium, both in scale and in technology.

I’d particularly like to draw your attention here to the Blue-spotted stingray, Taeniura lymma. This is an animal that is being put into danger by collection for the marine aquarium industry and features in the IUCN Red List of Threatened Species. It’s of particular concern as it has a poor record in captivity with a significant number of those brought in for public aquarium display failing to survive the acclimation process. If public aquaria, with their knowledge and facilities, find these difficult animals what chance do hobbyists have of keeping them alive?

Carangidae (Jacks).

Few, if any, fishes from this family are suitable for the home aquarium. The Golden Trevally, Gnathanodon speciosus, is my poster fish for animals that should not be imported unless ordered specifically for a public aquarium display. It is completely irresponsible for these fishes to be imported and held as a matter of course, it’s inevitable they’ll end up in the wrong hands (i.e. outside the public aquarium industry) when picked by people ignorant of the size of these fishes. At 6 -7 cms it’s a cute colourful fish, full grown at 120 cms, it becomes something that smaller public aquaria may have problems housing.

Wild Caught Clownfishes.

You might find this one a bit of a surprise but it makes complete sense. Every Clownfish taken from the wild means the potential demise of its host anemone, a potential that becomes even greater when it’s a pair that’s been collected.

All Clownfishes can be bred in captivity with differing degrees of difficulty, and contrary to uninformed opinion the colours of captive bred fishes can be just as vibrant as those of wild ones.

Ribbon Eels.

Rhinomuraena quaesita, with its nasal extension is a very striking fish. It’s unique amongst the Muraenids in displaying sexual dichromatism, males and female being differently coloured. It’s a protandrous hermaphrodite starting off life black, as it changes to male it takes on the very attractive blue colouration associated with this fish, finally becoming female at around 85 cms when the colour changes to yellow or yellowish green/blue.  These fish are difficult to feed, rarely surviving for more than a year in an aquarium; consequently, the female colouration is seldom seen in captivity.

Wild Caught Banggai Cardinalfishes.

Perhaps another surprise, but this is a classic example of an animal that is easily bred in captivity yet endangered in the wild by the aquarium industry. This fish inhabits a limited range; it produces small broods, and is limited in the number of broods it can produce over the course of the year.

Obligate Corallivores.

Unless you’re prepared to devote a separate aquarium to coral cultivation, one that can keep up with the demands of the fishes being kept, you shouldn’t buy any obligate corallivores. These are fishes that are obliged to eat coral polyps as a mainstay of their diet. Typified by Butterflyfishes plus the gorgeous Blue-spotted filefish Oxymonacanthus longirostris.

Mandarinfishes.

This one is difficult for me as, along with many other aquarists, this is one of the fishes that attracted me to the hobby in the first place. There are two concerns about Mandarins the first is a question of nutrition but if carefully considered there’s no reason why these fishes can’t survive their natural lifespan in an aquarium. The second is harder to defend and is concerned with the manner in which these fishes are collected. There is a tendency for the largest males to be targeted for collection, which has been proved to have a deleterious affect on the local population.

Cleaner Wrasses.

Labroides dimidiatus, the familiar blue cleaner wrasse, is a perpetual concern. They’re commonly seen for sale at a moderate price yet the majority of them are doomed to death by malnutrition. They’re obligate cleaners that feed on external parasites, mucus, and fish scales. To survive long-term they need to be kept with a large community of fishes. There is no excuse for an aquarist with an average sized reef to go out and purchase one of these fishes as, even though these fish will be seen to feed, they are unable to properly assimilate aquarium foods and will die prematurely.

Importantly, they cannot be considered a cure for diseases such as white spot - one of the main reasons hobbyists purchase this fish.

Cowfishes & Boxfishes.

Ostracion cubicus, Yellow or Cube Boxfish, Lactoria cornuta, Longhorn Cowfish, etc. are often seen as cute little “croutons” about 2 cms cubed, hovering in dealers’ sales tank, these are not fish to be taken on lightly. With an adult size of around half a metre, and the potential to wipe out a complete system with the toxic slime that they exude when stressed, they certainly represent a species unsuitable for the average marine aquarist.

SAIA

As I said at the beginning of this article, I’m currently compiling a list of unsuitable fishes for SAIA, if you would like to suggest any species that you believe should be included in this list please contact me at: tim@midlandreefs.co.uk

Tim Hayes

Midland Reefs

©2008 ©2010

Researchers from Tel Aviv University zoology department have reported previously unknown behaviour regarding feeding in a Large Polyped Stony Coral.

Whilst carrying out a survey dive of Fungiids, Mushroom Corals, on reefs off of the coast of Eilat the researchers took photographs documenting Fungia scruposa feeding on, Aurelia aurita, Moon Jellyfish. Previously, scientists believed these corals to feed on zooplankton in the range 0.2 to 0.4 millimetres in size.

Photo courtesy of TAU.

This is the first documentation of a coral feeding on a jellyfish almost equal to its size. F. scruposa can grow to around 30 cms in diameter while A.aurita ranges from 5 cms up to 40 cms in diameter. The fact that corals are capable of devouring prey several orders of magnitude larger than previously thought - was unknown to science until now.

Aquarium observation.

Although I’ve not seen this behaviour myself, I have come across something tantalisingly similar. A few years back I was maintaining a dozen or so juvenile specimens of Cassiopea species, Upside Down Jellyfish, at around 2 cms in diameter. Needing some extra room to accommodate some juvenile Fungia species of around the same size, I added the corals to the Jelly tank without a second thought. Within a couple of days I started to see jellies being injured by the corals and had to separate the two species.

Now although reef scientists may have thought that these corals only eat small zooplankton, in captivity it’s obvious that Fungiids are quite capable of coping with far larger prey items, my Fungia are regularly fed adult PE Mysis which can be up to 2 cms in length. It’s interesting to note that these corals do appear to have a sizeable mouth in comparison to other coral species, a 10 cm diameter specimen of mine has a mouth around 3 cms in length. Given this large mouth size it seems that they may be adapted to a larger prey size, although their main mode of feeding is to catch small particles on their upper surface which are then slowly transported to the mouth.

Tim Hayes

Midland Reefs

©2010

Genus Coryphopterus

Sand Gobies

Most, although not all, of these small gobies live on sandy substrates, feeding on diatoms, detritus, micro-crustaceans, and other small invertebrates.

Useful for sand maintenance in smaller aquaria such as nano tanks.

The majority of this genus is to be found in the Western Atlantic / Caribbean waters although a small number of species can be found in the Pacific. Consequently I’ve split the species list into separate Atlantic and Pacific categories. (See note in Part 4, Genus Elacatinus.)

Female to male sex change. For aquarium pairs, or single male with multiple females, the introduction of a small group of juveniles will naturally produce a social group. Male may tend multiple broods of eggs from spawnings with multiple females.

Coryphopterus - Pacific

Coryphopterus urospilus - Redlight goby

Lives in the sand/rubble fringe of rocky reefs or coral patches, foraging on micro-crustaceans amongst the rocks. When foraging over sand, the orange spots may act as camouflage. Dart about quickly and dives for cover when disturbed.

Coryphopterus (Pacific) - 3 species described

Ref. www.fishbase.org

Coryphopterus - Atlantic

Coryphopterus glaucofraenum - Bridled goby

Inhabits clear white sandy areas near deep reefs and grassy and rocky areas. Burrows in the sand and the male guards the eggs.

Coryphopterus (Atlantic) - 13 species described

Ref. www.fishbase.org

Tim Hayes

Midland Reefs

©2010

Genus Amblygobius

Hover Gobies.

Spend much of the time “hovering” above the substrate on the look out for food. Most species appear to be omnivorous, some are substrate sifters but in general there does seem to be a correlation between the presence of filamentous algae and success in keeping these species. Likely what appears to be herbivory in some of these species is actually a reliance on epibenthic organisms i.e. the small flora and fauna living on the algae.

Can be kept in pairs depending on the size of the aquarium.

In the wild many of these species use various invertebrate burrows for shelter.

Commonly available aquarium species:

Amblygobius decussatus - Orange-striped goby, Crosshatch Goby

9.5 cms

Substrate sifter.

Amblygobius hectori - Hector’s Goby

8.5 cms

Inhabits sheltered bays and inner reefs on fine rubble shaded by large living corals. Occurs solitarily, hovering a short distance above sandy bottoms of reef bases. Stomach contents of one specimen comprised filamentous algae, harpacticoid copepods, ostracods, amphipods, and nematodes.

Amblygobius phalaena - Banded goby

15 cms

One for the larger aquarium, where it can be a useful addition as a substrate sifter. Inhabits coastal reefs and lagoons on sand and rubble margins of algal reefs and sometimes near seagrass beds. Feeds by sifting mouthfuls of sand and expelling it through the gills, to capture small invertebrates, detritus, and algae. Monogamous.

Amblygobius 14 species described

Ref. www.fishbase.org

Genus Koumansetta

You may be wondering why Amblygobius rainfordi - Old glory or  the Court Jester Goby, perhaps the most well known of these fishes, wasn’t included in the above list. In July 2009 it was decided that the valid name for this fish was: Koumansetta rainfordi - Old glory. (See note below)

Currently there is just the one species in this genus.

Koumansetta rainfordi - Old glory

8.5 cm SL, Western Pacific

Depczynski and Bellwood describe this fish as having an average total length of 5.6 cm with the smallest at 4.54 cm TL (possibly down to the geographical area being studied) and (along with others) believe this represents the smallest documented adult size for a herbivorous marine fish and that it may define the lower size-limit for a herbivorous marine vertebrate.

Inhabits sandy and muddy bottoms of turbid coastal reefs to depths pf 20m, unlike others in its former genus it doesn’t appear to use a burrow.

Note:

Taxonomy, or biological classification, is the science of finding, describing and categorising organisms. As with all areas of science, this is best considered to be an ongoing work in progress, resulting in organisms being subject to re-classification and name change. In fishes, as a rule of thumb, about 10% of the names in any given work will be outdated after 10 years (Froese).  As DNA is becoming more widely used as an additional tool of biological classification, I’d expect see a lot more re-classification and name change occurring in the future.

Tim Hayes

Midland Reefs

©2010

Genus Elacatinus

Cleaner Gobies.

Formerly know as Gobiosoma, these are small fishes ranging from just over 1.5 cm up to 5 cm in length.

The most familiar of these are the cleaner goby complex, consisting of around 6 species, typified by E. oceanops - Neon Goby. These are fish that provide a cleaning service, removing ectoparasites from other, larger fishes.

Other fishes in this genus are known for their association with sponges, particularly tube sponges such as Callyspongia and Verongia.

The majority of this genus is to be found in the Western Atlantic / Caribbean waters although a small number of species can be found in the Pacific. Consequently I’ve split the species list into separate Atlantic and Pacific categories.

I believe it to be a bad idea to mix species from these two different oceans for a number of reasons, including potential vulnerability to unfamiliar pathogens and parasites, and the failure to recognise unfamiliar threat signals and react accordingly.

This is one area where Nano Aquaria work well, making it easy to keep just a few Atlantic organisms without succumbing to the desire to top up the fish population with the more common Pacific species.

Can be kept in pairs or small groups. May be intolerant of later additions of the same or similar species. Reputed to be monogamous but may pair seasonally.

Elacatinus - Pacific.

Some of the more common aquarium species:

Elacatinus puncticulatus - Red Head Goby

Inhabits rocky reefs, usually found in the vicinity of the urchin, Eucidaris thouarsi.

Elacatinus (Pacific ) - 6 species described

Ref. www.fishbase.org

Elacatinus - Atlantic

Some of the more common aquarium species:

Elacatinus multifasciatum - Greenbanded Goby

Inhabits pitted limestone faces and tide pools in surf areas in clear waters. Usually found among spines of rock-boring sea urchins. A protogynous hermaphrodite, this fish has been successfully reared in captivity

Elacatinus evelynae - Sharknose goby

Although a single species, there are three distinct colour forms of this fish, yellow, blue, and white, that occur in separate geographical areas.

This is a trait common to a number of other species in this genus.

Elacatinus oceanops - Neon Goby

Inhabits coral heads. Removes ectoparasites from other fishes. Was one of the first ornamental marine fishes to be reared in captivity.

In addition to Elacatinus oceanops the “Cleaner” species complex includes: E evelynae, E Figaro, E genie, E illecebrosus, E prochilos, and E randalli.

Elacatinus (Atlantic) - 28 species described

Ref. www.fishbase.org, Colin,

Tim Hayes

Midland Reefs

©2010

Genus Trimma and Trimmatom.

Pygmy Gobies

Small colourful fishes ranging from just over 1.5 cm up to 4.5 cm in length, found on reef habitats shallower than 80m.

Diet consists mainly of micro-crustaceans such as copepods and amphipods, etc.

Small cryptic fishes, such as Trimma species, can represent between 45 to 90% of the total fish population across a number of different reef zones; these are fishes with short life spans, fast growth rate, and a rapid generational turnover. Given their abundance it is likely that they represent a very important link in the food chain - think fast food of the reef.

One interesting feature of these fishes is that they exhibit two-way sex change. A fair amount of information is available on Trimma okinawae looking at its sexual behaviour both on the reef and in aquaria. It is probable that this information also applies to many other Trimma species.

Two-way sex change, or bi-directional sex change, means that these fishes can, depending on circumstances, change from male to female and back again whilst remaining sexually functional. Social groups of T. okinawae usually consist of a large male and one or more smaller females, with social groups being separated from each other by a distance of 1-3 m. In the wild, the larger the male, the greater the number of females belonging to the group.

Female-to-male sex change is more common than male-to-female sex change and occurs when the male disappears from the group through predation; in aquarium usage this would be expected to also occur but be due to the male reaching the end of its life span. In the wild either the largest remaining female changes sex to male or a large female from another group joins and changes sex to male. Larger individuals appear to benefit from becoming male because they can maximise their breeding opportunities with several females, as reported in other protogynous fishes. Sex change from male-to-female only occurs when a solitary male joins a new group as a subordinate member.

As with Eviota species, life span is of concern, with Trimma rubromaculatum and Trimma tevegae, being reported to live for between 12-20 months.

Accurate identification of Trimma species is difficult unless you’re a fish taxonomist; as a result fishes in the marine aquarium trade are likely to be misidentified. Consequently you may find yourself purchasing a fish at high cost that may only have weeks to live.

At a later date I hope to update the table to include details of lifespan.

Some of the more common aquarium species:

Trimma cana - Red Striped Goby

Trimma macrophthalma - Flame goby

Bottom-dweller on seaward reefs

Trimma okinawae - Okinawa rubble goby

Inhabits clear coastal reefs, near sponges to about 30 meters depth Usually found upside down in small caves on the reef

Trimma rubromaculatus - Red Spotted Goby

Inhabits rubble slopes at the base of vertical cliffs. Typically hovers vertically or obliquely, several centimetres above the bottom

Trimma striata - Stripehead goby

Usually lives in caves and crevices of outer reef slopes as well as occurring in deep lagoons and protected seaward reefs.

Trimma 63 species described

Ref, www.fishbase.org, Randall and Delbeek,

Genus Trimmatom

Trimmatom nanus

In 1981, at the time this species was described, it was claimed that  Trimmatom nanus was the smallest living vertebrate, with females reaching maturity at 8 - 10 mm SL.

Trimmatom 5 species described

Ref.  www.fishbase.org, Winterbottom and Emery.

Tim Hayes,

Midland Reefs

©2009

Genus Eviota.

The Pygmy Gobies

Small fishes ranging from just over 1 cm up to 4 cm in length.

Diet consists mainly of micro-crustaceans such as copepods and amphipods, etc.

Small cryptic fishes, such as Eviota species, can represent between 45 to 90% of the total fish population across a number of different reef zones; these are fishes with short life spans, fast growth rate, and a rapid generational turnover. Given their abundance it is likely that they represent a very important link in the food chain - think fast food of the reef.

Accurate identification of Eviota species is difficult unless you’re a fish taxonomist; as a result fishes in the marine aquarium trade are likely to be misidentified. Consequently you may find yourself purchasing a fish at high cost that may only have weeks to live, see Eviota sigillata, below.

At a later date I hope to update the table to include details of lifespan.

Some of the more common aquarium species:

Eviota bifasciata - Twostripe Pygmy Goby

3.5 cm TL. Inhabits clear coastal reefs and protected outer reef coral habitats. Usually at moderate depths of 10 meters or more, swimming near sponges or corals when feeding on plankton. Hovers in groups above branching corals of protected reefs.

Eviota sigillata - Seven-figure pygmy goby.

3.0 cm TL. A paper in 2005 reported this fish to have the shortest lifespan of any vertebrate, only living for 59 days. The species lives for 59 days at the most, with larvae spending three weeks in the open ocean and maturing within two weeks of settling on a reef, leaving the adults (which are 1 to 2 centimetres long) just three weeks to reproduce. This strategy of ‘live fast, die young’ strategy is perceived to be a response to intense predation. Daily mortality rate, from tag-recapture data, might be as high as 8%. Occurs at depths less than 4 to between 17 and 21 m on sandy bottoms of lagoon reefs.

Eviota - 54 species described

Ref: www.fishbase.org, Martial Depczynski.

Tim Hayes

Midland Reefs

©2009

Genus Gobiodon and Paragobiodon – Coral or Clown Gobies.

Commensal species usually associated with Acropora species in the wild.

Will happily perch in or on many corals in captivity although probably best to include some branching SPS corals for a more natural approach.

These species are reported to produces toxic mucus as a defence against predatory fishes.

Sex change species, so best to introduce small, young fish to avoid problems of mixing adults where the sex may already be fixed. Pairs off readily.

Harmless to most other species but aggression can occur amongst fishes of the same species and of similar species. Aggression seems to be a product of territorial requirements so this will depend on tank size.

Pairs may strip flesh from SPS corals when spawning to provide a site for the their eggs – not a problem for healthy corals. Good candidates for captive breeding programs.

May help protect SPS species from parasites such as the “Red Acro Bug”

As far as common names go, “coral” and “clown” seem to be interchangeable.

Where a species has 2 common names listed, the first mentioned is the Fish Base Common Name, which I consider to take precedence over aquarium common names given their inconsistency, country to country.

Some of the more common aquarium species:

Gobiodon atrangulatus - Clown Goby.

3.5cm TL

Gobiodon citrinus - Poison goby (Citron Clown Goby).

The giant of the genus at 5.6 cm TL. Has been raised in captivity.

Gobiodon histrio – Broad-barred goby (Green Coral Goby).

3.5 cm TL

Gobiodon okinawae – Okinawa goby (Yellow Clown Goby).

3.5 cm TL. Occurs in aggregations of 5-15 individuals in the wild.

Gobiodon spp. – A number of other species of similar size but varying attractiveness are also available in the trade.

Gobiodon – 20 species described.

Ref. www.fishbase.org.

Genus Paragobiodon

Paragobiodon lacunicolus – Blackfin coral goby (Panda Coral Goby).

3 cms TL. Lives exclusively among the branches of the coral Pocillopora damicornis, sometimes as deep as 20 m.

Paragobiodon melanosomus – Dark coral goby (Black Coral Goby),

3 cms TL. Paired individuals occur in colonies of Seriatopora spp.

Paragobiodon – 5 species described.

Ref. www.fishbase.org.

Tim Hayes

Midland Reefs

©2009