Sexselective fisheries

Males of many coral reef fish species tend to be preferred due to their distinctive coloration. Male mandarinfish, Synchiropussplendidus, for example, bear attractive dorsal fins and displays170. Male wrasses, such as the bird wrasse Gomphosus varius, and the sapphire devil Chrysiptera cyanea, are also often preferred to plain-looking females37. Such brightly coloured specimens are also likely to fetch higher prices on the market. Selectively harvesting for males of particular populations on a regular basis may lead to reproductive failure and ultimately population collapse due to heavily biased sex ratios in remaining schools (i.e. reduced male biomass)171,172.

Male sea goldie, Pseudanthias squamipinnis.

SPECIES SUITABILITY Fishes

Michael131 gives each species of fish an aquarium suitability index rating from 1 to 5 (see box) giving an indication of that species' durability, hardiness, and/or adaptability to captive conditions and food. Factors such as readiness to feed, dietary breadth, competitiveness, tolerance of sudden changes and ability to withstand less-than-ideal water conditions have been taken into account when applying a rating. For example, a species typically loses one rating point on this scale if live food is required.

Two of the most traded fish species (see Tables 46, pp 20-21), the mandarin fish and the bluestreak cleaner wrasse, have an aquarium suitability ranking of 2, indicating that they do not acclimatize well to aquarium conditions. Two others, the powder blue tang

Female sea goLdie, Pseudanthias squamipinnis.

(Acanthurus leucosternon) and the palette surgeonfish (Paracanthurus hepatus), have an aquarium suitability ranking of 3 indicating that they are relatively sensitive to aquarium conditions. All other of the most frequently

Michael's aquarium suitability index131

1. These species are almost impossible to keep and should be left on the reef.

2. Most individuals of these species do not acclimatize to the home aquarium, often refusing to feed, and waste away in captivity.

3. These species are moderately hardy, with most individuals acclimatizing to the home aquarium if species care is provided.

4. These species are generally durable and hardy, with most individuals acclimatizing to the home aquarium.

5. These species are very hardy with almost all individuals readily acclimatizing to aquarium confines.

Table 13: Top ten species of ornamental fish according to datasets derived for the United States, the EU and worldwide, and their suitability for aquaria according to criteria defined by Scott Michael and John Brandt

Where labelled 'na', no suitability code is assigned for this marine ornamental fish species according to Scott Michael and/or John Brandt. See box and text for explanation of codes.

Species Suitability Suitability code code

(Michael) (Brandt)

Species Suitability Suitability code code

(Michael) (Brandt)

Abudefduf spp.

na

na

Acanthurus Leucosternon

3

na

Amphiprion oceLLaris

4

na

Amphiprion percuLa

4

na

Chromis viridis

4

na

Chrysiptera cyanea

5

na

Chrysiptera hemicyanea

na

na

Chrysiptera parasema

5

na

DascyLLus aLbiseLLa

na

na

DascyLLus aruanus

5

na

DascyLLus trimacuLatus

5

na

Labroides dimidiatus

2

B

NemateLeotris magnifica

5

na

Paracanthurus hepatus

3

na

Pomacentrus austraLis

na

na

Pseudanthias squamipinnis

4

na

SaLarias fasciatus

4

na

Synchiropus spLendidus

2

B

Zebrasoma fLavescens

4

na

Table 14: Species classified as most unsuitable for maintenance in aquaria by Scott Michael and John Brandt

Species' names, quantity traded and most frequent country of origin

according to exporters' and importers' data in GMAD.

Species

Suitability code

Common name

Quantity traded

Most frequent country of origin

(Brandt)

(Michael)

(exps' data)

(imps' data)

(exps' data)

(imps' data)

Holacanthus arcuatus*

A

na

Black-banded angel

-

l3l

-

Unknown

Chaetodon austriacus

A

l

Blacktail butterflyfish

2

48

Sri Lanka

Saudi Arabia

Chaetodon baronessa

A

l

Eastern triangular

450

1,318

Indonesia

Indian Ocean

butterflyfish

Chaetodon bennetti

A

l

Bluelashed butterflyfish

6O3

811

Indonesia

Indian Ocean

Chaetodon capistratus

na

l

Foureye butterflyfish

-

5,280

-

Caribbean

Chaetodon larvatus

A

l

Hooded butterflyfish

504

l9l

Saudi Arabia

Yemen

Chaetodon lunulatus

A

l

Redfin butterflyfish

5O

-

Saudi Arabia

-

Chaetodon melapterus

A

na

Arabian butterflyfish

l4

-

Bahrain

-

Chaetodon meyeri

A

l

Scrawled butterflyfish

421

l23

Indonesia

Indian Ocean

Chaetodon octofasciatus

A

l

Eightband butterflyfish

2,025

421

Solomon Islands

Indian Ocean

Chaetodon ornatissimus

A

l

Ornate butterflyfish

648

l49

Philippines

Indonesia

Chaetodon plebeius

A

l

Blueblotch butterflyfish

233

1,712

Fiji

Fiji

Chaetodon reticulatus

A

na

Mailed butterflyfish

232

45

Philippines

Indian Ocean

Chaetodon speculum

A

l

Mirror butterflyfish

939

236

Philippines

Indian Ocean

Chaetodon triangulum

A

na

Triangle butterflyfish

85

130

Indonesia

Indonesia

Chaetodon trifasciatus

A

na

Melon butterflyfish

863

874

Sri Lanka

Fiji

Ginglymostoma cirratum

na

l

Nurse shark

-

632

-

South America

Labroides phthirophagus

A

l

Hawaiian cleaner wrasse

-

5,338

-

USA

All Labropsis species

A

na

Tubelips

94

33

Indonesia

Indonesia

(about 6 species]

Myrichthys colubrinus

na

l

Harlequin snake-eel

294

2,532

Philippines

Indian Ocean

Orectolobus maculatus

na

l

Spotted wobbegong

-

23

-

Unknown

Oxymonacanthus

A

l

Harlequin filefish

l,393

15,731

Philippines

Fiji

longirostris

* Also known as Apolemichthys arcuatus or Desmoholocanthus arcuatus. See box p 43 and text for explanation of codes.

traded fish species have been allocated suitability ratings of either 4 or 5. (See Table 13 on the previous page.]

John Brandt, an experienced aquarium hobbyist, categorizes fish species according to two lists, which are dynamic and continually open to revisitation and revision"".

List A: These species have the most disappointing record of captive care. They are the truly unsuitable species, dominated primarily by obligatory feeders such as coral-eating butterflyfishes. In most cases aquarists regard these species as impossible to maintain in captivity and many feel that they should not be collected for the aquarium trade. In general, relatively few of these animals are collected, as demand is much lower than with other species. There should be almost universal agreement among aquarists that these species do belong in this category, and not on List B.

An analysis including all species in GMAD and listed with a suitability code of 1 according to Michael131 or classed in list A by Brandt showed that the following species were traded the most: the harlequin filefish (Oxymonacanthus longirostris], Hawaiian cleaner wrasse (Labroides phthirophagus], foureye butterflyfish (Chaetodon capistratusl, harlequin snake-eel (Myrichthys colubrinus], blueblotch butterflyfish (Chaetodon plebeius], eastern triangular butterflyfish (Chaetodon baronessa], melon butterflyfish (Chaetodon trifasciatus], bluelashed butterflyfish (Chaetodon bennetti], nurse shark (Ginglymostoma cirratum], eightband butterflyfish (Chaetodon octofasciatus] (see Table 14]. All these species with the exception of Ginglymostoma cirratum are difficult to keep in captivity due to their restricted diets. Nurse sharks are common in the aquarium trade although, with a growth rate of approximately 19 cm a year in captivity, they will almost certainly outgrow all home aquaria131. Furthermore, they are highly predatory, often eating other organisms kept in the same tank131. Myrichthys colubrinus is a very selective eater whilst the remaining species are obligate corrallivores, meaning

The harlequin filefish, Oxymonacanthus longirostris

The harlequin filefish, Oxymonacanthus longirostris

In 1998 an extensive bleaching event was observed in reef areas worldwide. This event severely impacted the fringing reefs of Bise, off the northwest coast of Okinawa, Japan, with most of the living coral dying and filamentous algae quickly covering the dead corals. Of all species, acroporid corals seemed the most susceptible to bleaching174,175. Among coral-reef fishes, the species that are most likely to be affected by coral disturbances are obligate coral-dwelling or coral-feeding species, including butterflyfishes (Chaetodontidae)176. In response to the bleaching event,

Chaetodon trifasciatus and Chaetodon trifascialis showed significant declines in abundance. The small (maximum 9 cm) harlequin filefish, Oxymonacanthus longirostris, typically inhabits shallow coral reefs in the Indo-West Pacific and spends most of the day feeding almost entirely on the

polyps of corals of the genus Acropora . It lives in an exclusive and heterosexual pair, with the male and female sharing the same territory to feed.

Growth rates of adult Oxymonacanthus longirostris during coral bleaching were significantly lower, and tagged harlequin filefish were found to disappear at rates significantly higher than in previous years. In March 1999, no juvenile, young or adult fish of this species were observed at the site. This species is known to exhibit high site fidelity178, and abundance of Oxymonacanthus longirostris on surrounding reefs where the bleaching event was less severe was low, so the fish inhabiting this site seem to have died as a result of bleaching. Considering this species' diet, the study clearly indicates that the occurrence of healthy acroporid corals is essential to the survival of this species in the wild. High collection rates of this fish for the aquarium trade in addition to the higher frequency of natural disaster events such as bleaching observed in recent years may genuinely put at risk local populations and drive stocks below their critical recovery level.

Source: Kokita and Nakazono they feed exclusively on live coral polyps, a diet that cannot be duplicated in normal aquarium conditions.

List B: These species have a disappointing record of captive care. Very few individuals acclimatize to captivity or thrive over time. When individuals can be maintained, the lifespan is usually reduced. Feeding and nutrition are the primary cause of difficulties. Experienced aquarists or those using special techniques may have limited success with these species. Overall, much more research should be conducted on these species to determine the best methods for proper husbandry, or if any of these should be included on List A.

In general, there is a reduced demand for these animals and so fewer are collected compared with the more hardy species. Some aquarists would argue that a number of species on this list should not be included. These aquarists feel that there are enough documented cases of success to regard the species as being suitable. List B includes (as too extensive for full inclusion in this report): all seahorse and pipefish species, bicolour angelfish Centropyge bicolour, keyhole angelfish Centropyge tibicen, scribbled angelfish Chaetodontoplus duboulayi, bluespotted ribbontail ray Taeniura lymma, bluestreak cleaner wrasse Labroides dimidiatus, Moorish idol Zanclus cornutus, all dragonets and all parrotfish species.

The COMPLETE guide to Aquariums

The COMPLETE guide to Aquariums

The word aquarium originates from the ancient Latin language, aqua meaning water and the suffix rium meaning place or building. Aquariums are beautiful and look good anywhere! Home aquariums are becoming more and more popular, it is a hobby that many people are flocking too and fish shops are on the rise. Fish are generally easy to keep although do they need quite a bit of attention. Puppies and kittens were the typical pet but now fish are becoming more and more frequent in house holds. In recent years fish shops have noticed a great increase in the rise of people wanting to purchase aquariums and fish, the boom has been great for local shops as the fish industry hasnt been such a great industry before now.

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