Tangs & Surgeonfish Breeding Overview - Acanthuridae

Tangs & Surgeonfish Breeding Overview - Acanthuridae

Postby Colby » Mon Mar 12, 2007 9:02 pm

The Family Acanthuridae
This family covers about 72 different species encompassing 6 different Genera: Acanthurus, Ctenochaetus, Nasinae , Paracanthurus, Prionurus and Zebrasoma. Fish in this Family is commonly referred to as tangs, surgeonfish and unicornfish (Naso). Many of these species are popular additions to aquariums, e.g.
Acanthurus leucosternon - the "Powderblue tang"
Ctenochaetus hawaiiensis - the "Chevron tang"
Paracanthurus hepatus - the "Palette surgeonfish"
Zebrasoma flavescens - the "Yellow tang" makes up c. 80% of the fishes caught along the west coast of Hawaii Island for the aquarium trade. The total catch of Z. flavescens has recently approached half a million individuals per year (1) as the fishery has expanded greatly over the past two decades.

For an overview of the Acanthuridae, see http://www.fishbase.org/identification/ ... &areacode=

2 – Common characteristics:
All surgeonfish are laterally compressed and covered with very small scales giving their bodies a leathery appearance. They have long continuous dorsal fins, and small terminal mouths with fine teeth. What really distinguishes the whole family though is the presence of one or more spines on the caudal peduncle (the part of the body right before the tail fin), hence their scientific name from the Greek, acanthus = "thorn". With a twist of the tail these spines are used as a formidable weapon when needed (1).

Members of this group are usually classified as herbivores. Although herbivory predominates in tangs, including grazing on microalgae/filamentous alga covered substrates, flesh benthic (CaulerpaN. tuberosus) and floating macroalgae (SargassumN. unicornis, N. lituratus), some species are omnivorous and also feed on zooplankton (A. thompsoni, most Naso) and crustaceans (A. lineatus) (12).

3 – Reproduction:
3.1 – Sex determination:
Surgeonfish are gonochoristic (each fish is either male or female) (7).

3.2 – Sexual organization:
Solitary to large aggregations (schools).

3.3 – Sexing:
It may be difficult to determine the sex of surgeonfish. For Z. flavescens, some evidence point to differences in genital openings, which is easiest determined on close inspection (4). For A. nigrofuscus and Naso species the male tend to be larger than the female (6, 7).

3.4 – Courtship:
The courtship consists of males performing a shimmering movement to entice the female to spawn. The pair rises together toward the surface in an arc shaped path, simultaneously releasing their gametes into the open water at the apex of the arc (7). Z. flavescens has been observed to rise as high as 15-20 feet above the corals (9). Males may spawn with several females in a single session, while sexually mature females spawn only about once a month (7). Spawning rises are rapid, as the fish are exposed to predators when up in the water column, but often the egg/sperm clouds are preyed upon by plankton feeders. Each spawning rise is led by a female, followed by several males. Once spawning is over, fish stream away from the aggregation site, back to their feeding areas (3).

3.5 – Spawning:
Depending on the species, surgeonfish spawn in aggregations (ex.:A. mata, A. nigrofuscus, A. triostegus, C. striatus) or as pairs (ex.:A. leucosternon, A. nigricauda, A. dussumieri and many Naso and Zebrasoma species) (12). Many species can spawn either way and A. lineatus, despite forming spawning aggregations, spawn in pairs (12). An interesting spawning habit is reported to Ctenochaetus striatus from Tahiti. They form schools of several thousand individuals near full moon, remain motionless for between 1 to 3 hours and change their normal color to pale gray. Then, a group of 4 or 5 fishes rise above the main school, spawn and return to former place. This goes one with a new group replacing the previous one (12).

Often resident aggregations occur at a specific time of day often over many days, even year-round, and last a few hours or less (3). Many of the surgeonfish display seasonal patterns in fecundity, although the few specific studies of reproductive seasonality within the Acanthuridae have shown substantial differences in annual spawning patterns among species. Z. flavescens has been observed to spawn year-round, although egg production is reduced in the winter (9). Other species that seem to have annual spawning patterns are Acanthurus nigrofuscus and A. triostegus, but such patterns may vary according to geographic region, e.g. A. triostegus spawn year-round in American Samoa but has a distinct spawning period in Hawaii. Captive Z. flavescens, on the other hand, harvested from Oahu and Hawaii Island have been found to spawn during all months of the year, so data from nature may not be transferable to captive conditions (7).

4 – Eggs:
Eggs from Z. flavescens is shown on the picture below.
Image
(Photo courtesy: Syd Kraul)

4.1 – Size:
Z. flavescens: 650-800 um (8, 9).
Paracanthus hepatus – 710um (11).

4.2 – Quantity:
For Z. flavescens in the wild, large individual variation in batch fecundity has been observed, with a range from 44 to >24 000 eggs per female produced on a single sampling date. Smaller females (80–120 mm), produced limited numbers of eggs, while larger females (≥120 mm) were capable of maximal egg production (>20 000 eggs per batch) (4).

4.3 – Characteristics
Eggs are pelagic and have a single oil globule

4.4 – Incubation period/Hatching temp:
The fertilized eggs will move away in the plankton and hatch about 15-16 hours later (8).

5 – Larvae:
Z. flavescens larvae, 8 days old:
Image
(Photo courtesy: Syd Kraul)

After hatching, the pelagic larvae subsist on their egg yolk for a couple days and on day four start to feed on copepod nauplii and other small plankton (7, 8 ). They then begin to develop into a specialized larva, becoming compressed and growing thorns on the dorsal and ventral fins. Their bodies lack scales and are transparent with a silver cast to the abdomen. This post larvae stage is called 'acronurus larva', and is distinct to the Acanthuridae. As they grow the body becomes oval, the spines on the caudal peduncle develop, and the thorns on the fins gradually disappear (except on some of the Naso species and on Paracanthurus hepatus) (7).

Z. flavescens larvae, 24 days old:
Image
(Photo courtesy: Syd Kraul)

The planktonic stage will last about 10 weeks and then the young settle into a shallow reef. Though the behaviour of the young will vary between species and with the availability of food, many are initially quite territorial. As they mature most species become less aggressive and begin to roam wide areas of the reef in large schools (7).

Z. flavescens larvae, 40 days old:
Image
(Photo courtesy: Syd Kraul)

5.1 – Size at hatching:
Z. flavescens: 1.3 mm.
Acanthurus monroviae2,5 mm (12)

5.2 – Yolk sac present at hatch:
Z. flavescens: Yes.
5.3 – Mouth present at hatch: No
5.4 – Eyes developed at hatch: No

6 - Rearing:

6.1 - Breeding & Rearing Techniques
No one has succeeded in breeding species in this family yet, although spawning has been observed in many aquariums. At the Oceanic Institute in Hawaii Z. flavescens spawning behaviour has been observed in the evenings in 5000 L tanks that are 10-12 feet high (9, 10). One of the major obstacles is getting the fish to spawn. Since they perform spawning rises they need to have adequate room in the tank for this behaviour. Z. flavescens has been observed to spawn in tanks with less than 3 feet height (Waikiki Aquarium and at Dr. Syd Kraul's farm).

Another major obstacle to successful breeding is feeding the larvae. So far a gradual attrition is seen from day 1 post-hatch. Feeding with rotifers and brine shrimp has not been successful (8). At the Oceanic Institute in Hawaii, the local Parvocalanus copepod nauplii, and even their eggs, has also been tried with limited success (10). Another possible explanation to the attrition may be water quality, with the presence of microbial species, like bacteria, causing a problem (8).

6.2 – Day at first feeding:
2-3 days post hatch.
Paracanthus hepatus – day 3 post hatch (when yolk has been resorbed, mouth open and eyes show pigment) (11).

6.3 - Starvation Time:
Paracanthus hepatus – day 5 to 6 (11).

6.4 – Feeding scheme:
Very little information, as well as success, is available on the rearing of tangs larvae. Nagano et al, in the paper on P. hepatus, recorded survival until day 8 when larvae were fed, starting on day 2 post-hatch, Amphorellopsis acuta cilates (at 1,0 x 10*4 cells/L) and Gyrodinium sp. (3,1 x 10*6 cells/L).
No larvae found past day 8…

6.5 – Age at meta:
Size at metamorphosis for A. nigricans is 5.5 to 6 cm (12).

7 – Species been reared successfully:
None. The record is, to our knowledge, keeping the larvae alive to 42 days post hatch, achieved by Dr. Syd Kraul.

8 – References
(1) Williams, I. D.,Walsh, W. J., Claisse, J. T., Tissot, B. N. & Stamoulis, K. A. (2009). Impacts of a Hawaiian marine protected area network on the abundance and fishery sustainability of the yellow tang, Zebrasoma flavescens. Biological Conservation 142, 1066–1073.
(2) Tropical Marine Centre, http://www.tmc-ltd.co.uk/fish-invertebrates/surgeonfish.asp
(3) The Society for the Conservation of Reef Fish Aggregations, http://www.scrfa.org/images/stories/pdf/species/surgeonfish.pdf
(4) Bushnell et al (2010). Lunar and seasonal patterns in fecundity of an indeterminate, multiple-spawning surgeonfish, the yellow tang Zebrasoma flavescens. Journal of Fish Biology. 76, 1343–1361.
(5) Bushnell, M. E. (2007). Reproduction of Zebrasoma flavescens: oocyte maturation, spawning patterns and an estimate of reproductive potential for female yellow tang in Hawaii. Master’s Thesis, University of Hawaii, Manoa, HI, USA.
(6) Kiflawi and Mazeroll (2006). Female leadership during migration and the potential for sex-specific benefits of mass spawning in the brown surgeonfish (Acanthurus nigrofuscus). Environ Biol Fish. 76:19–23.
(7) Animal World, http://animal-world.com/encyclo/marine/information/breedmarine.php#Tangs
(8) Dr. Syd Kraul, personal communication.
(9) Dr. Bushnell, personal communication.
(10) Stephen Van Kampen-Lewis, personal communication.
(11) Nagano N. et l Effects of marine ciliates on survivability of the first-feeding larval surgeonfish, Paracanthurus hepatus: laboratory rearing experiments. Hydrobiologia 432: 149–157, 2000
(12) Fishbase, http://www.fishbase.org/identification/specieslist.cfm?famcode=412&areacode=

9 - Compiled By
Trond Erik Vee Aune - Agathos
Last Update: July 9, 2010.
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Re: Tangs & Surgeonfish Breeding Overview - Acanthuridae

Postby Agathos » Mon May 10, 2010 4:06 pm

Edit: The working copy has been moved to the first entry. --A Berry
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Re: Tangs & Surgeonfish Breeding Overview - Acanthuridae

Postby Agathos » Tue May 11, 2010 4:36 pm

I'll just keep editing my post above until I have exhausted the topic. Am I doing okay here?
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Re: Tangs & Surgeonfish Breeding Overview - Acanthuridae

Postby "Umm, fish?" » Wed May 12, 2010 5:28 pm

You are doing really well. Thank you. I didn't want to post in here because I didn't want to clutter your overview. But I can edit my comments out later. Thanks, again!
Andy

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Re: Tangs & Surgeonfish Breeding Overview - Acanthuridae

Postby Agathos » Fri May 14, 2010 2:45 pm

"Umm, fish?" wrote:You are doing really well. Thank you. I didn't want to post in here because I didn't want to clutter your overview. But I can edit my comments out later. Thanks, again!


Thank you. I have been in talks with Dr. Kraul and Dr. Bushnell and they have been exceedingly helpful. Hopefully I will have some pictures attached soon, too, courtesy of Dr. Kraul.
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Re: Tangs & Surgeonfish Breeding Overview - Acanthuridae

Postby Agathos » Sun May 16, 2010 4:41 pm

I am still in dialogue with some Acanthuridae experts, but I think my suggestions are more or less complete now. And since I won't be doing more literature search I can move on to the next Breeding Overview and update this as new information comes my way. But before I start on the next Breeding Overview I need to know how to do it. Is it okay that I reply to the existing Overview with my own suggestions to changes/additions, or perhaps a whole new version of it, like here, or should I rather post somewhere else?
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Re: Tangs & Surgeonfish Breeding Overview - Acanthuridae

Postby Midnight Angel » Sun May 16, 2010 5:02 pm

I would just like to thank you Agathos for taking the time to do this. This is great and again THANKS SO MUCH :!: And so your question isn't lost...........BOD please read Agathos last post here. :wink:


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Re: Tangs & Surgeonfish Breeding Overview - Acanthuridae

Postby aomont » Sun May 16, 2010 6:03 pm

Agathos, the overview came out amazing, good work !
In my opinion, you can continue doing as you did with this one. Later if will be split from the original and the comments so it can stand as the main overview.
Thanks for the help !
Anderson

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Re: Tangs & Surgeonfish Breeding Overview - Acanthuridae

Postby aomont » Sun May 16, 2010 10:08 pm

Sorry Agathos, I may have jumped the gun a bit.
Talk to Carl or Andy (I don't remember which one was in charge of overview committee) so they take note of who is doing which overview.
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Re: Tangs & Surgeonfish Breeding Overview - Acanthuridae

Postby aomont » Fri Jul 09, 2010 3:18 pm

Updated. ;)
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