Rising Tide Intern Joe Frith

Hello Everybody!  My name is Joe Frith and I have been interning here at the Tropical Aquaculture Laboratory in Ruskin, FL for the past 2 months. I would first like to say “thank you” to Dr. Judy St. Leger, Eric, Kevin, Roy, Craig, Jon and the rest of the staff here at the Lab for giving me this opportunity and making this a meaningful experience. I’m currently an undergraduate at the University of Missouri-Columbia completing my degree in Fisheries and Wildlife with a minor in Biology

Larval Rearing of the Purple Mask Angelfish

3 day old P. venusta larvae.  Photo credit: Karen Brittian. Larval rearing trials began with the spawning of a Paracentropyge venusta pair in the summer of 2013. The first successful larval rearing trial started with a small spawn on November 13, 2013.  This was the fifth larval run with this species and the focus was on food density and consumption at different developmental phases.  The diet consisted of both cultured copepods and wild collected plankton with all food items being less than 100 microns in size.  To assess consumption rates, five random samples were taken for initial food counts at the start of each test period. All food items added to the larval tank during the test period were counted while maintaining a density of 1 to 2 food items per ml in the water column. At the end of the time period counts were again done to determine larval consumption. At this point a 75% water change was carried out. I was surprised at the amount of food these little larvae could put away and as an example, at day 28 post hatch the larvae consumed approximately 2,150 food items each over a 12 hour period, (5:00am to 5:00pm). 32 day old P. venusta larvae.  Photo credit: Leighton Lum.   At one month of age the larvae started targeting larger prey items and ignored the food items less than 100 microns in size. At this point newly hatched and enriched Artemia were added to the diet along with adult cultured copepods.  The larvae also began to display benthic behavior by associating with the corners of the tank, the air stone and airline tubing.  A piece of dried coral rubble was added where the larvae took shelter.   The larvae continued to grow and develop; they were moved into a growout tank at 57 days old.  At this point we had 17 larvae remaining which equates to 6% survival from hatch. The development of juvenile colors came slowly. On day 95 they had black pigment on parts of their fins and tail.  A month later at 130 days old they were the beautiful blue and yellow of the adults. 115 day old P. venusta juvenile.  Photo credit: Leighton Lum.  Larval rearing of this species proved relatively “easy” in their first few weeks of the larval stage after which point larval development and growth seemed to slow. This could be attributed to the type and amount of wild plankton collected and fed out at that time. I feel that the larval phase could be shortened and improved upon in the area of diet. After metamorphosis the larvae were again slow to develop with a reluctance to accept non-living food items and this is also another area for improvement. The Reef Frenzy and Herbivore Frenzy frozen foods were the first choice of the juveniles when they began to accept non-living food. Currently these juveniles are fairly bold and are consuming frozen and dry foods with gusto.

Brood Stock Management, Spawning and Egg Collection of the Purple Masked Angelfish (Paracentropyge venusta)

Female P. venusta (note the light precaudal band).  Photo credit: Leighton Lum.Paracentropyge venusta were identified as a good candidate for captive breeding since they often do not adjust well to captive life after being collected in the wild. A juvenile pair from Japan was established for broodstock. The immature fish were introduced to each other during quarantine. Due to the timid nature of this species, quarantine was a dark blue barrel with black plastic pipe provided as hiding places. Male P. venusta. Photo credit: Leighton Lum. The pair is housed in a 440 liter tank with a foot print of 122cm by 46cm and a height of 76cm to provide room for a spawning rise. They are housed with a pair of Red Sea Regal Angelfish, Pygoplites diacanthus and a single Multibarred Angelfish Paracentropyge multifasciata. Feeding occurs at least 3 times daily with a varied diet of frozen clams, table shrimp, Mysis shrimp, krill, Artemia, commercial frozen and dry food and nori. The mature male now measures 8.5cm total length; the female is slightly smaller at 7.5cm. The female has a 1-2mm, pale colored band at the precaudal region of the body. This band is present in small juveniles and may be a simple trait of sexual dimorphism for this species. Spawning began when the pair was just over two years of age.  Initial spawns were small and infrequent.  During the summer of 2013, spawns became increasingly larger with a higher fertility rate although still on an irregular cycle.  Spawns are now more regular and vary 300 to approximately 1000 eggs.  Pre-spawning chasing activity generally begins around 7:00pm which is 2 hours before lights out.  Spawning normally happens within 30 minutes of lights out. The eggs are approximately 700 microns in diameter with a single oil drop. They are positively buoyant and float at the water surface.  The eggs are then collected using a 500 to 600 micron mesh net. They are placed in a container with water from the broodstock tank and allowed to incubate over night without aeration.  Once the eggs begin to develop, the embryo becomes heavily pigmented appearing quite dark as compared to other angelfish eggs. This makes them easy to see and count. Fertile eggs hatch 16 hours after spawn at 27C. Special thanks to DJ Lineham of Tropical Fish Emporium for broodstock acquisition and species information.

CORAL Video: Sulawesi Reef at Henry Doorly Zoo

http://www.youtube.com/watch?v=FSI5GQx65q0  (we strongly suggest you watch this one full-screen, in the highest HD setting your monitor will support!) Tim Morrissey, Coral Aquarist at Omaha’s Henry Doorly Zoo and Aquarium, recently shared this wonderful extra-high definition video of the Sulawesi Reef at Henry Doorly. The system is around 20,000 gallons, with the actual display being about 10,000 of that total water volume. Morrissey filled us in that the system has been through a few renovations over the years; currently he is the lead aquarist in charge of this display, having taken over in the summer of 2013 when another aquarist departed the zoo. The 10,000 gallon display area houses hard coral, soft coral, clams, anemones and lots of fish. You’ll see a periodic surge that occurs during this feeding time video; Morrissey told us this is accomplished with a pneumatic valve operated by compressed air that opens and closes to dump water in the tank.  The display is lit with 1000w and 400w metal halides; calcium supplementation is done with kalkwasser. A special thanks to Tim Morrissey for filling in some of the details on this unique aquarium.  For those who are curious, Morrissey filmed this with a GoPro Hero 3 Black Edition.
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