Captive-bred Centropyge venusta at 115 days post hatch. Image by Leighton Lum.
By Karen Brittain
Courtesy Rising Tide Conservation Updates Blog
Larval rearing trials began with the spawning of a Centropyge venusta pair in the summer of 2013. (Ed: This species was formerly known as Paracentropyge venusta and Centropyge venustus, no longer valid names.)
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.
Adult Purplemask Angel adult. Image by Scott W. Michael.
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 days post hatch the larvae consumed approximately 2,150 food items each over a 12 hour period, (5:00am to 5:00pm).
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.
Captive-bred C. venusta at 32 days post hatch. Image by Leighton Lum.
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.
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.
Purplemask Angelfish at day 115 with unknown larva. Image by Leighton Lum. Check back next week for update by the author.
Credits
From materials published by the Rising Tide Conservation Update. Reproduced by permission of the author.
About Reef Frenzy marine foods.
About the Author
Karen Brittain is a marine biologist at the Hawaii Institute of Marine Biology, University of Hawaii – Manoa. She lives in Kailua and is a participant in the Rising Tide Conservation Initiative.
