Rising Tide Conservation researchers Dr. Matt DiMaggio, Dr. Cortney Ohs, and Avier Montalvo recently presented at Aquaculture America in San Antonio, Texas. If you were unable to see our fantastic researchers live, we have the presentation abstracts for you here!
DETERMINING PREY PREFERENCE OF FIRST FEEDING MARINE ORNAMENTAL FISH LARVAE UTILIZING FLUORESCENT MICROSPHERES
Cortney L. Ohs*, Isaac Lee, Jason S. Broach, Matthew A. DiMaggio, Craig A. Watson
As the popularity of marine aquaria grows, potentially more marine ornamental fishes and invertebrates will be harvested from the oceans. Aquaculture of marine species is a sustainable alternative to wild caught individuals and may help to grow businesses and diversify species in production. Experiments were conducted with first-feeding larvae of Reef Butterflyfish (Chaetodon sedentarius), Pacific Blue Tang (Paracanthurus hepatus), African Moony (Monodactylus sebae) and Golden Trevally (Gnathanodon speciosus). The objective was to define prey preferences at first-feeding between rotifers (Brachionus plicatiilis), copepod nauplii (Parvocalanus crassirostris), and ciliates (Euplotes sp.), by marking each prey with a different color of fluorescent microsphere and observing gut contents with a fluorescent microscope. Each fish species showed different prey preferences. Pacific Blue Tang larvae preferred rotifers above ciliates, and ciliates above copepod nauplii. African Moony larvae preferred ciliates and nauplii equally over rotifers. Reef Butterflyfish larvae preferred ciliates over rotifers and rotifers over nauplii. Golden Trevally larvae preferred nauplii over ciliates, and ciliates over rotifers.
This study presents a new understanding of prey preference of first feeding ornamental marine larvae by utilizing fluorescent labelled microspheres. Microspheres are currently used in marine ecology research to trace microplastics throughout planktonic food webs. Ingestion of naked ciliates labeled with microspheres in fish larvae has been previously performed. However, microspheres have not been utilized to examine prey preference and consumption of live feeds. This marks the first use of microspheres in aquaculture with rotifers (Brachionus plicatilis) and copepod nauplii (Parvocalanus crassirostris).
A school of Golden Trevally at the Georgia Aquarium
INFLUENCE OF ABIOTIC FACTORS AND FOOD CONCENTRATION ON POPULATION GROWTH OF THE CILIATE Euplotes sp.
Cortney Ohs*; Wesley Freitas da Annunciação; Mônica Yumi Tsuzuki
Live food organisms used for feeding larval marine fish have received significant research in the past decade. Most of this research and development has focused on rotifer enrichments and feeds, and mass scale production methods for several species of copepods. However, there is a need to investigate other small live food organisms to potentially improve survival and growth of larval fish during the hatchery phase of culture. One potential live food organism is a ciliate. However, there is a dearth of information on optimal production parameters for ciliates. The objectives of this study were to evaluate the influence of abiotic factors including salinity, photoperiod, temperature, aeration, and food concentration on the growth of Euplotes sp. populations. Five replicated small scale experiments were designed and conducted. First, food concentrations of 50, 100, 250, and 500 mg of Protein Selco (INVE) per million ciliates were investigated. Second, salinities of 15, 20, 25, 30, and 35 g/L were investigated. Third, four levels of aeration were investigated. Fourth, temperatures of 17, 20, 23, 26, 29, and 32°C were investigated. Fifth, four photoperiods were investigated.
Results indicated that the optimal range of conditions for production of the ciliate Euplotes sp. tobe a feed concentration of Protein Selco (INVE) of 250 mg per million ciliates, salinity from 20-35 g/L, low or no aeration, temperatures between 26 and 32°C, and a photoperiod between 0L:24D and 16L:8D. Based on the results and observations during this study, we conclude that the ciliate Euplotes sp. has characteristics favorable to mass production including resistance to adverse conditions such as high concentrations of ammonia and very low dissolved oxygen concentrations, they experience high growth and reproduction rates, can grow to very high densities, received nutrition either directly or indirectly from an inert diet, and adapted well to a wide range of salinities and temperatures.
RECENT ADVANCES IN THE CULTURE OF THE PACIFIC BLUE TANGParacanthurus hepatus
Matthew A. DiMaggio*, Eric J. Cassiano, Kevin P. Barden, Shane W. Ramee, Cortney L. Ohs, and Craig A. Watson
It is estimated that over 11 million marine ornamental fishes, representing approximately 1,800 unique species, are sold annually; with the preponderance of specimens resulting from wild capture. Growing interest in marine ornamental aquaculture has served as an impetus for efforts to commercialize new species for the industry and develop novel culture protocols. The Pacific Blue Tang, Paracanthurus hepatus, is consistently among the top twenty species imported into the United States by volume, with all specimens sourced from wild stocks. Captive culture of this species through metamorphosis has not been previously documented and fundamental information regarding reproduction, larval culture, and production techniques is scarce. This study aimed to elucidate methods that would advance our understanding and success with captive propagation of this species.
A total of 50,000 eggs were collected from a single broodstock population (1 male, 2 females) over a three day period in May 2016. The eggs were successively stocked in a 1000 L larval tank for a final density of 50 eggs/L. Beginning at 3 days post hatch (DPH) larvae were fed 3 times daily a diet comprised exclusively of the copepod nauplii (<75 μm, mean ± SD = 5.1 ± 2.3 mL -1 day -1 ) of Parvocalanus crassirostris. At 12 DPH, enriched rotifers Brachionus plicatilis (6.8 ± 3.2 mL -1 day -1 ) were first fed to the tank. At 20 – 21 DPH, powdered feed and first instar Artemia nauplii (1.1 ± 0.7 mL -1 day -1 ) were also added to the diet. Live microalgae (~3:1 of Tetraselmis chuii and Symbiodinium microadriaticum) were added daily to the culture tank throughout the rearing trial. Large mortality events were observed at 7 and 20 DPH corresponding with starvation and flexion, respectively. By 41 DPH, a behavioral change was noted with the majority of the remaining larvae associating with the bottom of the tank. On day 50, the first signs of blue pigmentation marked the beginning of metamorphosis. A total of 27 juvenile blue tangs were cultured during this trial. This effort represents the first successful rearing of this species in captivity and provides important information for future production studies.
Larval development of the Pacific Blue Tang
UNTAPPING THE RESOURCE: THE USE OF A MIXED SPECIES EXHIBIT AS A VIABLE SOURCE OF EGGS FOR MARINE ORNAMENTAL AQUACULTURE
Avier J. Montalvo*
The focus of this project was on marine ornamental reef species of importance to Hawaii. Eggs were collected from a partnering institution’s 166,000-gallon public exhibit. Eggs were collected and transported back to the Oceanic Institute (OI), where rearing attempts were conducted and documented. The goal was to culture new species and establish successful rearing protocols which could then be applied to other ornamental species that have not yet been aquacultured. The use of a mixed species exhibit for ornamental egg collection, and mixed-species larval rearing are relatively new approaches in marine ornamental aquaculture. Over the course of the project, a total of 794,760 eggs were collected across 28 collections with representative larvae from three different families of fishes. This led to the successful rearing of six different species, four of which had never previously been reared successfully in captivity. The successful collection, transport, and rearing of eggs from public aquaria gives merit to the mission of Rising Tide Conservation to preserve and protect coral reefs by means of sustainable aquaculture.
Larval development of Klein’s Butterflyfish, Milletseed Butterflyfish, Potter’s Angelfish, Longnose Butterflyfish, Hawaiian Cleaner Wrasse, and the Yellow Tang
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February 9, 2017 – Rising Tide Conservation, in partnership with the University of Florida Indian River Research and Education Center, is thrilled to announce the aquaculture of the Reef Butterflyfish (Chaetodon sedentarius)! This success is the first of 2017 for Rising Tide Conservation and Dr. Cortney Ohs and his fabulous team, including researchers Isaac Lee, Jason Broach, and Andrew Palau. Dr. Ohs writes the following about the history, procedure, and specifications for this fantastic accomplishment:
“We have one pair of Reef Butterflyfish (Chaetodon sedentarius) broodstock inside an 1800 liter round tank. They were acquired in May of 2015 from Marathon, FL, and were originally collected by Dynasty Marine. They began spawning three months later in August. They are fed four times a day with an Otohime EP1 pellet, PE Mysis, mullet roe, and Larry’s Fertility Frenzy. They spawn once every 2-3 days and produce approximately 3000-5000 eggs per spawn with >90% viable eggs. For this run, 3000 eggs were stocked out into a 440L fiberglass tank with black sides and a black bottom. The larval system was equipped with a 80 W UV sterilizer, two bag filters with 50 and 10 μm felt bags, a protein skimmer and trickle filter. One direct LED light was set on a 12 L: 12 D cycle and an ambient fluorescent light from an indirect source was on a 24 L: 0 D cycle. The tank was overturned 6x per day. Larvae were fed Parvocalanus crassirostris copepod nauplii (5.3/mL) twice a day and Brachionis plicatilis rotifers enriched with Selco S.presso (8.6/mL) once a day beginning 4 days post hatch.
Reef butterflyfish (Chaetodon sedentarius) larvae 1 day post hatch.
Reef butterflyfish (Chaetodon sedentarius) larvae 4 days post hatch.
Reef butterflyfish (Chaetodon sedentarius) larvae 7 days post hatch.
Reef butterflyfish (Chaetodon sedentarius) larvae 11 days post hatch.
Reef butterflyfish (Chaetodon sedentarius) larvae 14 days post hatch.
Reef butterflyfish (Chaetodon sedentarius) larvae 17 days post hatch.
T-Isochrysis was added twice a day and timed with feedings of copepod nauplii. At 20 dph, we incrementally began adding newly hatched Artemia nauplii to the diet twice a day starting at 0.01 /mL and reaching 0.2/mL over the course of 8 days.
Reef butterflyfish (Chaetodon sedentarius) larvae 20 days post hatch.
Reef butterflyfish (Chaetodon sedentarius) larvae at 24 days post hatch.
Reef Butterflyfish (Chaetodon sedentarius) larvae at 26 days post hatch.
Reef Butterflyfish (Chaetodon sedentarius) larvae at 28 days post hatch.
At 28 dph, we stopped feeding rotifers. At 34 dph, we stopped feeding copepod nauplii.
Reef Butterflyfish (Chaetodon sedentarius) larvae at 38 days post hatch.
We began feeding Otohime A1 dry diet at 43 dph. The last mortality was recorded at 36 dph. Survival for this trial was 0.1% for three individuals. The larvae remained a bland grayish coloration and then begin developing a black band that goes vertically across the eyes. The posterior edges of the dorsal and anal fins began to darken up. Then they developed a yellow ridge across the top of the dorsal fins. The body then began to turn a brighter white.”
Juvenile Reef Butterflyfish (Chaetodon sedentarius) at 108 days post hatch.
This photo of the juvenile Reef Butterflyfish is at 108 days post hatch. The fish begin to take on the adult coloration at about 70 days old. Photograph opportunities were limited from 70-108 days old, but we look forward to replicating the success and getting more pictures! We hope that you’ll continue to follow our successes and support Rising Tide Conservation!
The University of Florida Tropical Aquaculture Laboratory (TAL) is currently working with two species of wrasses; the Melanurus wrasse (Halichoeres melanurus) and the Yellow wrasse (H. chrysus). Three separate broodstock populations of the Melanurus wrasse are being maintained in various sex ratio and fed a varied diet 4-5 times per day to promote spawning behavior and ensure the production of high quality eggs. Consistent daily spawning from two of the Melanurus wrasse populations yields from 100 to over 2,000 fertile eggs, averaging 0.604mm in diameter. Preliminary larval rearing trials exploring the effects of varying environmental conditions in both large (125L) and small (13L) culture tanks have recently resulted in one successful larval run. Nine healthy, post metamorphic juveniles were raised during this run representing a survival of 1% from egg to juvenile. These juveniles are now over two months old (wrasses shown in the video are from this run and the video was taken two weeks post settlement). The first larvae from this run settled and completed metamorphosis at 37 days post hatch. While settlement appeared to be somewhat delayed when compared with our previous efforts, this cohort is the largest group of Melanurus wrasses raised thus far at the TAL. Efforts to repeat and improve upon this success are underway and will involve investigations into optimal incubation and larval rearing temperatures, stocking densities, light intensities, live feeds densities, and other culture parameters.
Melanurus wrasse eggs.
Melanurus wrasse, 2 days post hatch.
Melanurus wrasse, 22 days post hatch.
Three separate broodstock populations of the Yellow wrasse are also currently maintained and fed the same diet as the Melanurus brood stock. Highly variable spawning has been observed from both of the actively spawning populations resulting in eggs of poor quality and low fertilization. Egg diameters are currently averaging 0.575mm. Investigations focused upon improving egg quality and fertility are also under way.
The very first success for my project came with collection #3. The egg collectors were set on March 16, 2016. Eggs were harvested the morning of March 17, 2016. There were a total of 20,800 eggs with 11,648 viable (56%). The eggs were stocked at a fairly high density of 58.24/mL into a single 200L flow-through tank. The average rearing parameters for this egg collection was: 26.2 ± 1˚C and 30.0 ± 0.8 ppt. DO was maintained ≥ 6.0 mg/L, and pH ranged from 7.8 – 8.0.
Despite a somewhat low viability, there was a substantial hatch. I checked on the larvae each day, and at three days post hatch, I prepared to administer first feeding as well as background algae. The larvae were extremely tiny and it was hard to distinguish between species at such an early age. I added the first feeding of copepod nauplii, and I did not observe many larvae feeding. I figured this was due to relatively cool water temperature, which was approximately 25ºC at the time.
These larvae developed very slowly, and many died off within the first 5 to 10 days post hatch. Upon examining the larvae, all appeared to have fully developed eyes and mouths; however, many did not have full guts. I wasn’t exactly sure why some of them were not eating, but I continued to feed and monitor accordingly. The water quality checked out fine.
Milletseed Butterflyfish, 25 days post hatch
I was able to take a few good pictures at 25 days post hatch. The post-flexion larvae at approximately 6.13mm looked good. Very well developed eyes and mouth, and completely developed guts full of food. Dorsal spines were forming, and there was an increased amount of pigmentation, with a slight deepening of the body. Perhaps the most important observation was that the larvae had already entered their tholichthys stage of development, with bony plates forming around the head extending back towards the posterior end of the larvae.
Milletseed Butterflyfish, 40 days post hatch
Many of the larvae continued to drop for no apparent reason. The larvae at 40 days post hatch were 7.02 millimeters long, had substantial deepening of the body, and distinct dorsal and ventral spines. Fins were fairly well developed, and the gut was still appeared full of food. The larvae fed on nauplii, enriched rotifers, and newly hatched artemia. The bony plates, characteristic of the tholichthys stage were thicker and more prominent. This “helmet” was clearly visible on the heads of the larvae. Some of the larvae were also beginning to exhibit a silvery appearance.
The larvae continued to dwindle down to only a few. By day 60, there was a single lone survivor. There were a few scares with this larvae, particularly when it was nowhere to be found and was thought to be lost (quite a story). However, it pushed through, and settled at approximately 74 days post hatch.
For fear of losing this special larva, I held off on taking any photos until I knew it completed settlement. By 88 days post hatch, it was clear the mystery Chaetodontid was the milletseed butterflyfish, Chaetodon miliaris. Its juvenile coloration is seen in the following photo.
Milletseed Butterflyfish, 88 days post hatch
It was quite the journey, but this lone survivor was the first of its kind to be reared in captivity, and it too was cute at the about the size of a dime. It had quite the personality and loved being in front of the camera!
Egg collectors were deployed on the afternoon of 4/17/16 and collected on the morning of 4/21/16. There was a total of 32,900 eggs with 70% viability. This was the highest number of eggs collected to date. The eggs were stocked at a density of 23.03/mL in a 1,000L flow-through tank. The average rearing parameters for this collection were: 26.8 ± 1˚C and 30.0 ± 0.8 ppt. DO was maintained ≥ 6.0 mg/L, and pH ranged from 7.6 – 7.8.
Most of the larvae Avier examined had well-formed eyes, mouths, and guts, with the yolks fully absorbed. The first feeding of copepod nauplii and background algae was provided. It looked like larvae were either Acanthurid (tang) or Chaetodontid (butterfly). At approximately 30 dph there was a different larva. A very different larva. Pictured at 35 dph, at approximately 8.80 mm in length, was a long and slender larvae, spending most of its time around walls of the tank, picking prey items off the side. The larvae had very well developed eyes, and a fully formed mouth and gut. It did not have a very deep body, but it did have well-formed fins, with blotchy speckles of pigment starting to develop.
Hawaiian Cleaner Wrasse at 35 days post hatch.
The larva was elusive but it showed up again while Avier was cleaning the bottom of the tank a few days later. A brightly colored neon blue streak shot up towards the surface of the tank! He caught the specimen and examined it under the microscope. It was a completely metamorphosed fish. But which fish?? The little guy was moved into a 200L flow-through tank with settled fish from another collection. Pictured at 41 dph, at a length of 13.88mm, the mystery fish had a neon, multicolored strip running from its head to tail, fully developed fins, and a round but slender body dark colored body.
Hawaiian Cleaner Wrasse at 41 days post hatch.
It was a Labroides phthirophagus, the Hawaiian Cleaner Wrasse! It was voraciously feeding on enriched artemia, frozen cyclopeeze, and flake. Interesting tidbit, this individual started exhibiting its cleaning behavior at 44 days post hatch (and the other fish in the tank did not like it!).
There is a single mated pair in the entire mix species tank. That pair produced an egg that produced a larva that turned into this fish. This fish is the first of its kind to be reared in captivity, and it has significant implications for the conservation. Pictured at 91 days post hatch, the juvenile exhibited the narrow mouth, pointed head, and bright colors characteristic of this cleaner species. The multi-colored stripe changed to resemble the distinctive purple coloration found on the adults, and the dark colored body was now jet black.
Hawaiian Cleaner Wrasse at 91 days post hatch.
At 118 days post hatch – the growing juvenile has changed color again. Here’s what he looks like today.
Hawaiian Cleaner Wrasse at 118 days post hatch.
The IUCN reports: Labroides phthirophagus inhabits coral and rocky reef habitats, other than within the surge zone. This species is an obligate cleaner, feeding on the crustacean ectoparasites of other fishes, probably including gnathiid isopods and also on fish mucus. While the population is not identified as endangered, the limited distribution of this fish makes them vulnerable to local environmental damage. As an aquarium fish, captive reared specimens that eat like locusts show great promise for the hobby.