Expansion and Diversification of Freshwater Tropical Fish Culture |
The overall goal of this project is to demonstrate to Hawaii aquaculturists the feasibility of ornamental fish production as a viable alternative cash crop. Specific objectives related to that goal are to:
Production of egg-laying tropical fish species has been hampered by lack of a hatchery to provide seedstock to farmers. Operation of a hatchery will allow the production sufficient quantities of fry for farmers to gain experience in growout, grading, sorting, transporting and marketing commercial quantities of these animals.
Providing technical assistance to farmers involved in this fledgling endeavor, the main focus of this project, will ensure that the industry gains a firm foothold. Training farmers in disease management for these animals is an important aspect of this technical assistance.
Objective: Operate an incubator hatchery for the production of 2-week-old larvae of selected egg-layers for distribution to Hawaii farmers.
Project personnel successfully establish broodstock of tinfoil barbs, rainbow sharks, albino rainbow sharks, tiger barbs and blue and gold gouramis at the project facility at Windward Community College. Maturation of selected broodstock species was monitored, and mature individuals were either induced or conditioned to spawn.
Three species of egg layers - rainbow sharks, red tail black sharks and tinfoil barbs - achieved gonadal maturation during the reporting period. These species require hormonal induction of final maturation and spawning of broodstock.
Tiger barbs and gouramis, which are characterized as temporary paired tank spawners, can be conditioned to spawn. Maturation drops sharply in October and November and does not appear to resume until March. This indicates that these species exhibit discrete spawning seasons, which would mean that farms culturing these species would also exhibit seasonal production.
Farmers would find the ability to control maturation and spawning in order to produce fish on demand advantageous. Technology to do so would provide farmers with the means to take advantage of seasonal fluctuations in the market. As a first step toward developing such technology, project personnel monitored environmental parameters, including water temperature and day length, that influence maturation and correlate them with seasonal maturation data for rainbow sharks, red tail black sharks and tinfoil barbs. The correlation clearly shows the day-length and water temperature at which the percentage of mature animals increases.
Objective: Expand technical assistance to more demonstration farm sites and include small-scale commercial breeders to increase production and diversification of species.
A total of 267,432 fry were produced and distributed to farmers during the reporting period. In addition, 5,592 broodstock of 10 species were distributed to farmers during the reporting period.
A series of disease management workshops was conducted in collaboration with Dr. James Brock. The workshops were held at the Cooperative Extension Service facility in Hilo and at the University of Hawaii at Hilo campus and attended by 85 individuals. The workshops, which repeated those held on Oahu during Fall 1996 under the "Ornamental Aquaculture Technology Transfer" project, were titled:
The workshop series will be repeated on Molokai with support from the Maui County Aquaculture Extension project.
Interviews with producers indicated several areas in which technical assistance could be provided to improve overall productivity. The first area was determining which feeds were best for these ornamental species. Very little information is available regarding nutritional requirements of ornamental fishes, so project personnel collaborated with small-scale commercial producers to determine which commercial feed for food fishes would be suitable for use with ornamental fishes.
A series of experiments compared a mahimahi feed, a salmon feed and a standard flaked feed. Results demonstrated that both the mahimahi feed and the salmon feed, which had feed conversion ratios of 0.8 each, were superior for growing marble angelfish and golden angelfish and are 10 times cheaper than the flake food tested, which had a feed conversion ratio of 1.3.
In addition, a palatability test designed by Dr. Harry Ako was conducted to determine whether the aquaculture feeds obtained superior results because fish preferred their taste. The five-day test carefully recorded the amount of one feed eaten by a group of fish in comparison to other feeds. Results indicated that the fish preferred the mahimahi and salmon feeds to the flake feed.
Tests were also conducted with the ornamental variety of carp, known as koi. These tests indicated that the koi preferred Laguna Supreme Formula and Hikari Gold feeds, which produced about three times the increase in both fish length and weight gain over the other feeds tested. This supports the hypothesis that more palatable feeds should yield faster growth than less palatable feeds.
Additional tests examined growth and survival of guppies fed a commercial salmon fry feed, a commercial trout chow, a grower's mix consisting of spirulina, trout chow, Lansy, mahimahi feed and egg yolk, and a pureed beef heart, beef liver and garlic custom mixed feed. Those fish given the beef-heart-and-liver mix had a significantly lower survival rate than those given the other three feeds. The lower survival rate resulted in large part from the poor water quality resulting from use of this feed mix. Feed conversion ratios for the first three feeds ranged from 0.6 to 0.7; an estimated feed conversion ratio for the beef-heart-and-liver mix was not obtained. The two commercial feeds were much lower in price. The results suggest that use of commercial feeds would yield good results at the lowest cost to the producer.
Feeds used in maturation and spawning of discus, angelfish, guppies, goldfish, gouramis and barbs were examined for total and essential fatty acids. Investigators were looking for similarities in the feeds' nutritional profiles. The feeds examined were live earthworms, mosquito larvae, moina, a beef heart preparation, black tubifex worms and red tubifex worms.
The results strongly suggest that a particular fatty acid plays an integral role in the reproductive mechanism of a large number of ornamental fishes. Interestingly, this fatty acid is different from that required by marine fishes.
Several workshops and short articles on the findings about
feeds were prepared. Workshops titled "Ornamental
Feeds," were presented to the
Goldfish Club of Hawaii in Honolulu on September 15, 1996;
Hawaii Tropical Fish Farmers Association in Hilo on October 5,
1996;
Backyard Aquaculture Hui on Maui on November 23, 1996; and
Honolulu Aquarium Society on April 4, 1997.
On June 5, 1997, investigators presented a workshop on ornamental fish culture at the University of Guam PEACESAT station. The workshop, which reached 51 PEACESAT stations in 22 countries, was a two-way, interactive audio broadcast. In addition, investigators conducted site visits and evaluations in Guam, Pohnpei, FSM, and Majuro, RMI. Only Majuro proved unsuitable for ornamental fish culture because freshwater resources and the transportation infrastructure are limited.
Investigators will analyze a survey of those who received fish from the project to determine their success rate. They also will present a workshop to address proper packaging and shipping methods for live aquarium fishes. In addition, they will continue to provide technical assistance to farmers.