Some day, tanks at aquaculture farms around the state and nation could be teeming with millions of colorful fish to help stock the nation’s aquariums.
At least that’s the dream for Syd Kraul and others who have attempted to strike the fine balance needed to rear species such as angelfish and yellow tang in captivity.
But that day isn’t today.
“Getting good survival of the larvae is the main problem, especially that first week,” said Kraul, owner of Pacific Planktonics in North Kona.
Kraul has several tanks set up at the Natural Energy Laboratory of Hawaii Authority, where he is raising flame angelfish, multicolor angelfish and yellow tang. The tang, in particular, is in high demand and very difficult to raise.
“Out of 10,000 eggs, you might get 200 to 300 larvae that survive the first week,” he said. “That’s not enough. By 90 days you won’t have any left.”
The 90-day point is when the fish move out of the surface water, change from clear to yellow and take up shelter in the rocks.
“People all around the U.S. are trying to do it, but you don’t hear much because they’re not succeeding,” Kraul said.
Kraul, who has been raising aquarium fish since 2006, thinks he finally has it figured out.
“It’s no secret. It’s just about getting the right balance of food in the water,” he said. “Put in too much food and the fish are going to die. You’re feeding itty-bitty larvae with food that’s not much bigger than bacteria. They need the food but they need clear water. That’s the challenge.”
Other researchers report making strides in culturing aquarium fish in recent years. The issue of creating a supply tends be an economic one, because it remains cheaper to collect fish from reefs than to rear them, said Chad Callan, a research scientist with the Oceanic Institute at Hawaii Pacific University. Callan has tried to propagate tang for more than a decade and has finally figured out how to get them past the first two months.
“I think we are in the home stretch with yellow tang,” Callan said in an email. “The real trick is turning a breakthrough in technology into a commercially feasible one.”
The infant fish subsist on juvenile copepods, which Kraul cultures in a separate tank. He has sold a few hundred aquarium fish over the years, but never enough to make it economically viable. To pay the bills, he raises species including milkfish, or awa, for golf course ponds. But Kraul plans to have a viable supply of flame angelfish within a year. The fish retail for about $50 in stores.
“People like them,” he said. “They live a long time. They’re colorful and you don’t have to be super careful what you feed them.”
Kraul — who sells his fish to aquarium collectors who in turn package and market them — hopes to offer yellow tang on a commercial basis within a year as well.
Fewer than a dozen tropical reef species can be cultured on a reliable basis, and efforts tend to be on a small scale and poorly funded, said Maria Haws, director of the Pacific Aquaculture and Coastal Resource Center at the University of Hawaii at Hilo.
“We could be doing a lot more both with aquarium and food fish if we had funding,” she said.
Just down the road from Pacific Planktonics, the owners of Ocean Rider Seahorse Farm also tried to raise the elusive tang. Craig Schmarr and Carol Cozzi-Schmarr made an eight-month effort to rear the fish last year, but gave up because the project was drawing too many resources from other areas. The farm’s chief focus has been successful propagation of seahorses, which it both sells for aquariums and displays on tours of its facility.
The farm has successfully raised and sold banded pipefish, clownfish and the rare Banggai cardinalfish — an exotic, sparkling fish native to Indonesia. The fish sell for $39, $49.50 and $19, respectively. Schmarr has held onto the yellow tang brood stock but has no firm plans for propagating it.
“Tangs are going to be a difficult thing to accomplish,” Schmarr said. “It’s always about meeting their nutritional requirements at an early age. It doesn’t seem to be a problem of getting them to spawn; it’s a problem of getting them through those early days.”