Rearing the Crested Oyster Goby

Mature pair of crested oyster gobies. Male above, female below

 

The field of marine ornamental aquaculture is truly unique. Unlike food fish aquaculture or pearl farming where end consumers gain a product bearing little resemblance to the live, cultured form marine ornamental aquaculture promotes the use of live, healthy fish for display and education. The aquarium industry has come a long way over the last few decades, and through a greater understanding of systems and species as well as technological advances in filtration systems end users commonly maintain these animals alive and healthy longer than their recorded lifespan in the wild. Aquarium enthusiasts, fueled by passion and curiosity, have thus contributed endless amounts of information regarding the captive care and culture of marine fishes. As the hobby of marine fish propagation grows so too does the information gathering and expansion into new species. Research and development necessary to bring new species into culture is often the most costly and time consuming task associated with expanding production. Aquarium hobbyists have played an integral role in bridging the gap between research and development and commercial production of new species. Commercial culture of the crested oyster goby, Cryptocentroides gobiodes is a fantastic story and a great example of hobbyist involvement.

Amy Drehmel, an accomplished breeder from South Carolina purchased three adult crested oyster gobies from Tideline Aquatics, her local aquarium shop, shortly after they became available in 2010. An Australian endemic, the crested oyster goby is rarely collected for the aquarium trade, likely due to its shallow, muddy, estuarine habitat and commands a high price when available. Amy’s initial investment for the fish was just shy of a car payment.

At the time, very little was known about the natural history of the species, how to tell the boys from the girls, how to initiate spawning, what to feed them, and how to approach larval rearing. Amy was one of the first aquarists in the U.S. to rear watchman gobies so she had a pretty good idea of what to expect.  Amy quickly succeeded in being the first person to raise this new-to-the-trade species in 2011.

At the Tropical Aquaculture Laboratory, we received eleven first generation (F1) offspring from Amy early last year (2012). The fish were immature and divided into two 20 gallon aquariums with plenty of PVC pipe and oyster shells to make them feel at home.  

Sexual maturity of our F1 offspring was reached in 180 days. Mature fish in good condition exhibit subtle traits of sexual dimorphism. Males are typically larger than females and exhibit enlarged first and second dorsal fins with brighter coloration. The first few rays of the first dorsal fin is elongated and pointed in males. Males display a somewhat more robust head and are overall lean in appearance compared to the rotund belly of females. Males can be aggressive toward conspecifics in small tanks and outside of reproductive periods. We recommend that groups of 6-8 fish be housed in 25 gallon (~100L) and larger aquariums at a ratio of one male to three or four females to diffuse aggression.  Spawning occurs from 73-82F with a photoperiod of at least 13 hours of light.  Feeding should consist of at least two daily feedings of commercial gel diets with frozen squid, shrimp, and fish flesh.

PVC sections containing eggs are removed from the guarding male in the broodstock tank 4 days after spawning. The PVC section is affixed vertically in the rearing tank with an airstone placed below. A steady stream of air is allowed to pass directly over the eggs to keep them in constant motion and facilitate hatching under dark conditions. Under these artificial conditions, if the air flow is too low or the bubbles do not come in direct contact with the eggs they will often fungus and fail to hatch. Hatching occurs roughly 30 minutes after the lights have been turned out.

Larvae have been reared in 13 L, 25 L, and 60 L black round tanks, glass aquariums, and commercial buckets.  After hatching, the air flow is turned down to approximately 100 mL/min. Larvae exhibit a strong feeding response under normal fluorescent lamps (6500 K double lamps) suspended 10 cm above the surface. First feeding is initiated the day after hatching when the larvae measure 3.2 mm in length.  Rotifers (Brachionus plicatilis - 200µm lorica length) are stocked at 5-10/mL as an initial diet.  Larvae tend to stack against the sides of the rearing tank until live phytoplankton or algae paste is added to the tank.

 

Larval development of crested oyster gobies from egg to settlement

Aeration is increased slightly at 3 dph (200 mL/min), which seems to help maintain water quality and aids feeding performance of larvae.  At 5-8 dph, Artemia nauplii are added at a density of 0.5-1/mL. Aeration and water exchange is increased sequentially as the larvae grow to maintain high oxygen levels and reduce waste build up in the tank.

Metamorphosis occurs between 13 and 16 dph when individuals undergo morphological and behavioral changes that, upon completion, result in a benthic juvenile. Upon completing metamorphosis, the juveniles are approximately 12 mm in length, a light tan color and active on the bottom of the tank. At this point, juveniles are weaned from Artemia nauplii to dry pellets (0.5 – 1 mm). Larval survival to the juvenile stage is typically higher than 80% although some runs seem to produce near 100% survival.

Although this species is most often reported from cooler, subtropical waters spawning, egg development, larval rearing, and juvenile growout occur unhindered in water temperatures ranging from 73 to 83F.

A culture protocol for the species, as well as broodstock animals are currently being produced and disseminated to commercial producers.  One commercial producer has already produced offspring that should be available to the trade soon.  From hobby to production…in the span of three years, three generations of crested oyster gobies have been produced, fine-tuning a protocol that has been used to get this species into commercial production.  

Matthew L. Wittenrich, PhD

Eric Cassiano

 

Tropical Aquaculture Laboratory

University of Florida

 

 

Hello all!

I would like to start my first blog post with a grand THANK YOU to the University of Florida Rising Tide team: Matt, Eric, Kevin and especially Judy St. Ledger for choosing me to join them in what is an incredible opportunity! Thank you to Dr. Roy Yanong, my academic advisor, University of Florida, the host institution for this whole program, and say thank you to Sea World and Busch Gardens for funding this project.

I am very excited to have started my position here at the UF’s Tropical Aquaculture Lab in Ruskin, FL. I have been busy in my first month. There is much to learn, observe, and understand from such a knowledgeable staff. Training is hands on here and I have been incorporated in numerous projects including system design and construction, aspects of fish health, broodstock husbandry and larval rearing.  Exciting enough as being incorporated into this program is; I have also raised several new species to me (grunts) and one new species to the lab (highhats) from eggs given to us by Discovery Cove. I am thrilled to have been thrown into the mix and have these results. The staff has taken me in as one of their own and is always willing to help. Great people do great things! 

As the newest member I am inclined to introduce myself to our associates and readers, whom I hope to have the pleasure of meeting at some point.

I grew up in Rhode Island—basically living in the ocean throughout my youth. I love fishing, freediving, boating, and every other activity involving the ocean. I attended Florida Institute of Technology in Melbourne, Florida for my undergraduate degree where I attained a B.S. in Aquaculture and Marine Biology. Growing up I had multiple saltwater tanks so I was drawn to work in the only lab on campus full of fish, the Aquaculture Lab under Dr. Junda Lin. I worked there for 4 years during my undergrad and gained valuable experience I would need to be a successful applicant for my current position with Rising Tide.

My position is part of the Rising Tide Initiative to raise marine ornamental species, with a concentration on Chaetodontids. I am working with the Milletseed Butterfly fish, Chaetodon miliaris, an endemic species in Hawaii. These are gregarious planktivores, unlike many species of butterflies, which are corallivorous or feed on coral. Large schools form over reefs feeding on zooplankton in the water column. Our broodstock just arrived from Quality Marine in Los Angeles, who graciously donated the fish in support of Rising Tide. We owe them immensely for being so gracious and supportive of the Rising Tide Initiative. The fish look fantastic and have acclimated well to their new home here at the Tropical Aquaculture Lab. This is just the first step of this project. The next steps will truly test my skills and the skills of the team. Our goals are to induce spawning in captivity in the Milletseed butterfly and then discover the secrets of larval chaetodontid species and other marine planktivorous species. We hope to understand the requirements needed to breed and raise Milletseeds so that we can use these techniques to rear similar species and transfer our knowledge to commercial producers so aquacultured fish will be in the marine ornamental trade not wild caught fish.

Again, I would like to say thank you to everyone contributing to my project: Rising Tide, Quality Marine, Sea World, Busch Gardens, and University of Florida.

Cheers,

Jon-Michael Degidio

Highhats at 20 days

Just a quick photo update of the recently raised highhats from Discovery Cove. Here, the juveniles, now at 20 days old, are over an inch long and developing their characteristic juvenile streamers.

Matthew L. Wittenrich

Eric Cassiano

University of Florida
Tropical Aquaculture Laboratory

Highhats from Discovery Cove

2013 is turning out to be a productive year at the Tropical Aquaculture Laboratory. As the calender year turned, we welcomed our newest member to the marine ornamentals team, Jon-Michael Degidio. Tasked with the rearing chaetodontids as part of Rising Tide's newest initiative, Jon knows he is in for a challenge. To hone his skills at larval rearing and prepare him for butterflies, we worked with aquarists at Discovery Cove to bring in a fresh batch of eggs collected in the Grand Reef. We know the Grand Reef is home to an incredible array of sought-after marine species and has huge potential in discovering a new species for aquaculture. In his first weeks at the lab, Jon has succeeded in raising highhats spawned in the Grand Reef. This was surely a welcomed surprise in our larval tanks and an encouraging first run from our newest member.

More updates and new species coming soon.
Special thanks to Denise Swider and the team at Discovery Cove for making this happen. 

Matthew L. Wittenrich

Eric Cassiano

Tropical Aquaculture Laboratory
University of Florida

Rearing Green Chromis

With nearly a million specimens imported into the United States each year, the green chromis, Chromis viridis, may well be the most popular fish in the marine aquarium trade (Rhyne et al. 2012). It is the most highly collected fish species appearing in the trade, beating out blue damsels by nearly 200,000 per year into the US (Rhyne et al. 2012). Although green chromis are widespread throughout the Indo-Pacific region and their populations probably in little threat of over exploitation, collection and transport methods are thought to claim high mortality through the chain of custody. Despite their popularity, little progress has been made in culturing this iconic species.

To our knowledge, the only successful rearing of green chromis was done in India by Gopakumar et al. (2009). In this study, they housed broodstock animals in roughly 480 gallon tanks. Larvae were reared in 1,200 gallon tanks that were previously seeded with two copepod species and phytoplankton and allowed to bloom.  Using these semi-extensive methods, researchers obtained ~5% survival.

Hatchery produced green chromis should prove far hardier and resistant to the stresses of capture and shipping compared to wild caught stock. To fill a pet shop with captive bred green chromis, however, aquaculture technologies need considerable advancements to achieve high survivorship with economical methods.

Recently, University of Florida’s Tropical Aquaculture Laboratory claimed its first victory in rearing green chromis from cultured live feeds produced on site. We received a few sporadic batches of green chromis eggs from SeaWorld, Orlando in 2012. From these early trials, we were able to identify what the larvae were feeding on. We then isolated a key copepod species and worked extensively to isolate and culture the copepod in high enough numbers to be used as a sole diet through larval development.

The broodstock animals are housed in the large Manta Reef Exhibit at SeaWorld, Orlando. Green chromis are generally open water swimmers feeding on zooplankton as it passes in the currents. When the fish are spawning, however, males will fall out of the schools and settle on the bottom to set up and defend short term breeding territories.  Justin Zimmerman and his team at SeaWorld look for this as a signal of breeding behavior and keep a close eye on the spawning substrates for eggs. At SeaWorld Orlando, the fish spawn on dead Acropora coral branches, which are plucked from the exhibit and transported to the Tropical Aquaculture Lab in small buckets.

Green Chromis eggs shortly before hatching. Photo by Eric Cassiano

 

At the lab, the coral branches are rubber banded together at the bases being careful not to damage the delicate eggs. They are suspended in the water column with fishing line and supplied with a strong flow of air from a 6” airstone placed on the bottom of the tank. The airflow keeps the branches and the eggs in constant motion, which is needed to mimic the action of the tending male and facilitate hatching. Hatching occurs on the 4^th night after spawning.

Unlike most damselfish, green chromis larvae are underdeveloped at hatching and lack pigmented eyes, a functional mouth and gut. At slightly more than 2 mm total length, the larvae subsist on protein and lipid rich yolk reserves that fuel development in the upper water column. Two days after hatching, the larvae are ready to feed, and must be supplied with tiny copepod nauplii to survive. Chromis larvae, in our experience, are highly selective in choosing their zooplankton prey. We offered cultured Oithona colcarva nauplii at a density of about 3/mL. The first feeding stage of marine fish larvae is typically characterized as the stage prone to the highest levels of mortality. We experienced little early mortality since the larvae fed aggressively on the cultured Oithona. Bottlenecks to culture developed after day 10 and 15 when the larvae required sequentially larger copepod prey. Flexion occurred near day 15, which was accompanied by our highest mortality rates. At this stage of development larvae undergo dramatic changes in morphology and reorganization of the gut. We suspect that mortality here is attributed to insufficient nutrition through early development.

Metamorphosis is slow from here and by day 35 the tiny juveniles measuring 10-12mm become more bottom oriented and display the schooling behavior so common to the species. The characteristic blue-green color is evident by day 40. Our first successful run resulted in just over two dozen juveniles. We are currently working hard to expand copepod production to supply copepodites and larger copepods as the larvae grow.

We are extremely proud of this accomplishment, partly because of the huge popularity of the species and partly because of the methods employed to overcome bottlenecks and achieve success. Determining what green chromis larvae consumed during first feeding was instrumental in our success. Isolating and culturing the live feed organism, while certainly challenging, proved successful.

Larval cycle of green chromis to 45 days post hatch

Special thanks to Justin Zimmerman, Gary Violetta, Denise Swider and the team at SeaWorld


Rhyne, A.L., Tlusty, M.F., Schofield, P.J., Kaufman, L., Morris, J.A., Bruckner, A.W. 2012. Revealing the appetite of the marine aquarium fish trade: the volume and biodiversity of fish imported into the United States. PlosOne.http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0035808

Gopakumar, G., Madhu, K., Madhu, R., Ignatius, B., Krishnan, L., Grace, M. 2009. Broodstock development, breeding and seed production of selected marine food fishes and ornamental fishes. Marine Fisheries Information Service T&E Ser. 201: http://eprints.cmfri.org.in/4190/1/1.pdf

 

Matthew L. Wittenrich, PhD

Eric J Cassiano

Kevin Barden

University of Florida 
Tropical Aquaculture Laboratory

Rearing French Grunt (Haemulon flavolineatum)

Subadult French Grunts raised at the Tropical Aquaculture Laboratory. Photo by Matt Wittenrich

Grunts of the family Haeumulidae are undoubtedly some of the most economically and ecologically important fishes of the western Atlantic. Anyone that has donned mask and snorkel and submerged into the turquoise water of the Caribbean has surely encountered one of the family’s representatives. Fifteen species of grunts are found in the region and often dominate (numerically) shallow reefs.  Their abundance on coral and rocky reefs, ledges and hard bottoms have led to a high value fishery (2.3 million pounds of grunts landed in Florida in 2005) and a greater understanding of the role these fishes play in food webs, both as predators and prey.  In aquariums, grunts have long been a favorite of public aquariums looking to create eye dazzling displays of underwater worlds. Schools of grunts, often numbering in the thousands, are a common site on Florida reefs. For species like the French Grunt (Haemulon flavolineatum), with a bright yellow body color set amidst horizontal and diagonal bands of fluorescent blue, this site can be simply stunning behind a glass pane.

Broodstock and Spawning

Despite the value and importance of this family little is known about the reproduction and early life history of the group. As part of the Rising Tide Conservation Initiative, the Tropical Aquaculture Laboratory has successfully raised five species of grunts. Development of culture techniques and development based photo guides have been hindered since most of our egg collection techniques have occurred in heavily stocked multi-species exhibits. This has made it extremely difficult to quantify the species and diversity of eggs we are stocking into larval tanks. Interspecific interactions among larvae and the different environmental and feed requirements have made it difficult to create species-specific rearing protocols.  Recently, the Tropical Aquaculture Laboratory partnered with the Seas with Nemo & Friends at Epcot Center, Walt Disney World to rear a large group of French Grunts for display, as well as develop the culture technologies that could make this commonplace. Disney’s research team found that their French Grunts were actively spawning in a behind-the-scenes research system and wasted no time hatching a plan.

According to Larry Boles, Disney researchers stocked 8 adult French Grunt measuring 10cm fork length in each of 6 replicated 660 liter recirculating systems. Within 3 weeks they observed spawning in all systems. Photoperiod was set to 12L:12D, water temperature around 26C, and water quality maintained with wet/dry biomedia and 20 micron cartridge filters. Water exiting the research tanks is gravity-flow to the biofilter through a dispersion bar onto a 100 micron prefilter material. Eggs spawned in the system make their way through the plumbing and collect on this filter material. Eggs are never totally submerged, but kept wet from the incoming water. The morning after spawning, Disney staff scrapes the eggs from the filter material with a metal spatula. Egg production was monitored by placing the eggs into graduated cylinders and measuring the total volume of eggs produced each day. From here, the eggs, now developing embryos, are placed in a 13 liter pail with clean seawater and transported to the Tropical Aquaculture Laboratory.

Overview of recirculating seawater systems at Disney used for spawning French Grunt. Photo by Larry Boles/Disney

660 liter recirculating seawater systems at Disney used for spawning French Grunt. Photo by Larry Boles/Disney



Gravity feed from broodstock tanks to biofilter. Eggs and debris are concentrated on prefilter material after spawning. Photo by Larry Boles/Disney





Eggs are removed from prefilter material with a metal spatula. Photo by Larry Boles/Disney



Eggs are sampled volumetrically to determine daily fecundity. Photo by Larry Boles/Disney

French Grunt embryos shortly before hatching. Photo by Matt Wittenrich

Embryo transfer and stocking

At the lab, floating embryos were carefully decanted from the surface of the bucket and homogenized in roughly 6 liters of clean seawater. The embryos in each liter of water were counted to make stocking the larval tanks easier. Larvae were reared in 13 liter, 60 liter and 350 liter tanks and stocked at 15 – 30 larvae/ liter. First feeding is initiated 2-3 days after hatching when the larvae measure ~ 2.8 mm total length.  Initial larval rearing trials utilized rotifers and copepod dominated wild plankton to observe maximum production potential. Rotifers were maintained at ~ 5/mL and copepods were stocked at ~ 2/mL every other day. . Live or paste Nannochloropsis oculata was used to tint the water during larval development. On day 15 newly hatched Artemia was added to the diet and greenwater was discontinued. At 20 days, rotifers were removed from the diet and 24 hr. enriched Artemia was added. Metamorphosis began near 25 days and extended until day 31 when all individuals displayed post metamorphosis morphology and behavior. At 20 days, a dry diet was introduced and Artemia was removed from the diet by day 35. Survival in these initial trials ranged from 43 – 85%. This is fantastic survival and resulted in a 350 liter tank, stocked with 4,000 embryos, producing over 3,200 juveniles.

Larval development of French Grunt from hatching to metamorphosis. Photo by Matt Wittenrich

In later trials, we found minor differences in growth and survival with cultured rotifers and copepods. Metamorphosis-stage fish were sensitive to shock from dietary HUFA deficiencies when fed un-enriched rotifers. This problem was often so severe that simply bumping the tank or walking too quickly towards it would result in near immediate death of dozens of larvae. This problem was not observed when prey was enriched with 2 x daily HUFA enrichments. Early juveniles were moved to 800 liter growout tanks at day 40.The French Grunt is well suited to commonplace aquaculture techniques. The larvae are large at first feeding and readily accept rotifers as an initial diet. Post metamorphosis growth is rapid with juveniles reaching 2 inches in just under 3 months.  

Special thanks to Larry Boles, Stacy Knight , Melyssa Allen, Nicole Uibel, Todd Harmon, and Jane Davis



Matthew L. Wittenrich, PhD

Eric Cassiano

Kevin Barden

Tropical Aquaculture Laboratory

University of Florida



French Grunts from Walt Disney World

The short video above shows a thriving larval rearing tank full of 18 day old French Grunt (Haemulon flavolineatum) spawned at Walt Disney World. The stocking density is certainly high, but the larvae have preferences for certain high-flow, high-light areas in the tank and seem to stack up in these areas, giving the illusion of a much higher stocking density. Days away from metamorphosis, this group of grunts has been used to document larval development, and to create a larval rearing protocol for the species. We were lucky enough to be contacted by Disney when their group of French Grunts starting spawning in a research system. This is a fantastic opportunity to examine the aquaculture requirements for French Grunts without interspecific competition from other species that we normally see in aquarium- collected spawns.

This species of grunt is similar to congeners in its larval rearing requirements and does very well on a diet of rotifers and Artemia and are sure to be an amazing, schooling display of yellow bodies and bright blue eyes.

More to come...

Special thanks to Larry Boles and Stacy Knight of Walt Disney World for their invaluable help in bringing this species to culture.

Matthew L. Wittenrich, PhD

Eric Cassiano

University of Florida
Tropical Aquaculture Laboratory