Rearing the Rare: Raising the Queen Triggerfish Balistes vetula. A Collaboration between Roger Williams university and the New england aquarium
Public aquariums have become very proficient at recreating natural environments for captive fish. This high level of attention and focus on natural settings, proper sex ratios, and high quality foods results in a significant amount of spawning in aquarium display tanks. Fish naturally spawn and produce healthy, high quality eggs and larvae. Generally eggs are lost in filters or preyed upon by other fish. If larvae are produced insitu, they are normally filtered out and these viable larvae are lost. The New England Aquarium and the Roger Williams University Center for Economic and Environmental Development (CEED) have joined together to collect and raise these larvae. Our first attempt was with the Queen Triggerfish, Balistes vetula, a popular fish in the aquarium industry and a food source in some countries. However, since 1996, the Queen Triggerfish has been listed on the IUCN Red List as a threatened species. At the New England Aquarium the Queen Triggerfish has spawned regularly in the Giant Ocean Tank (GOT) since their introduction in the 1970s. Triggerfish generally lay over 500,000 small demersal eggs that is heavily guarded by the parents. Eggs hatch within 48 hours and larvae are extremely small and underdeveloped compared to other demersal spawning species.
One day before hatching the Queen Triggerfish eggs were collected from the aquarium using SCUBA and transported to the RWU Marine Lab where the eggs were incubated. Upon hatching, 1,500-2,000 larvae were collected, moved to a rearing tank and in a green water environment and fed cultured copepods and wild plankton. During the first 25 days post hatch (DPH) the larvae were fed microalgae from the RWU Shellfish Hatchery and zooplankton. As an initial feed, the larvae were fed cultured Parvocalanus sp. copepods (until 15 DPH) supplemented with wild plankton (35-6510 DPH). After 15 DPH the larvae were fed only wild plankton (35-10010-25 DPH; 65-15025-35 DPH). At 35 DPH the juveniles were weaned onto a microdiet using wild plankton (105-200 and a commercial larval diet, Otohime Flexion was completed at around 20 DPH. Metamorphosis occurred after 40 DPH and varied based on individual. Throughout the rearing process, development and behavioral progress were tracked using general observations and photographs.
One day before hatching the Queen Triggerfish eggs were collected from the aquarium using SCUBA and transported to the RWU Marine Lab where the eggs were incubated. Upon hatching, 1,500-2,000 larvae were collected, moved to a rearing tank and in a green water environment and fed cultured copepods and wild plankton. During the first 25 days post hatch (DPH) the larvae were fed microalgae from the RWU Shellfish Hatchery and zooplankton. As an initial feed, the larvae were fed cultured Parvocalanus sp. copepods (until 15 DPH) supplemented with wild plankton (35-6510 DPH). After 15 DPH the larvae were fed only wild plankton (35-10010-25 DPH; 65-15025-35 DPH). At 35 DPH the juveniles were weaned onto a microdiet using wild plankton (105-200 and a commercial larval diet, Otohime Flexion was completed at around 20 DPH. Metamorphosis occurred after 40 DPH and varied based on individual. Throughout the rearing process, development and behavioral progress were tracked using general observations and photographs.