Mysterious breeding habits of aquarium fish vex experts

PENYABANGAN, Indonesia (AP) — Tom Bowling needed a broken air conditioner to figure out — after nearly eight months of failure — how to farm the coveted pink-and-yellow tropical fish known as blotched anthias.

Bowling, an ornamental fish breeder based in Palau, had kept the fish in cool water in an attempt to mimic the temperatures in which the deep-water animals are commonly found. But when the air conditioner broke down, the water temperature rose a few degrees overnight — with surprising results. “They started spawning — they went crazy and laid eggs all over the place,” Bowling said.

Experts around the world are tinkering with water temperature, playing with light and trying different mixtures of microscopic food particles in the hopes that they will happen under the specific and idiosyncratic conditions that will inspire ornamental fish to breed. Experts hope to divert the aquarium fish trade away from wild-caught fish, which often happens caught with poisons that can harm coral ecosystems.

CORRECT ATMOSPHERE REQUIRED

Most of the millions of glittering fish that circulate in saltwater aquariums in the US, Europe, China and elsewhere come from coral reefs in the Philippines, Indonesia and other tropical countries.

Trappers often numb them with chemicals such as cyanide. They are then handed over to intermediaries and then flown around the world, after which they end up in aquariums in homes, shopping malls, restaurants and medical offices. Experts estimate

“large percentages” die along the way.

Part of the problem: Only about 4% of saltwater aquarium fish can be bred in captivity, largely because many fish have extensive reproductive cycles and delicate early life stages that sometimes require mysterious conditions that scientists and breeders find difficult to reproduce.

For decades, experts have worked to unravel the secrets of marine fish farming. Breakthroughs don’t come anytime soon, says Paul Andersen, head of the Coral Reef Aquarium Fisheries Campaign, which is committed to supporting sustainable aquarium fisheries on coral reefs.

“It requires years of investment, research and development, often to take incremental steps,” he said. And then longer, he said, to bring new captive-bred strains to market.

The Moorish idol, a black and yellow striped fish with a mane-like dorsal fin back, needs a lot of space. Squiggle-striped green mandarins prefer to spawn just before the sun sets, requiring very specific lighting cycles to breed in captivity. As Bowling in Palau discovered, spotted anthias require very specific temperatures.

“You have to pay attention to all the parameters that make a fish happy,” Andersen said. “Some species are very gentle, delicate and sensitive to this sort of thing.”

FRAGILE EARLY DAYS

After the fish are spawned, breeders are often faced with the most challenging part of the process: the larval period, the time just after the fish hatches, before it develops into a juvenile. The water flow has to be just right, but they are so fragile that they need to be protected from filters and even tank walls.

The first feeding is also crucial, said Andrew Rhyne, a professor of marine biology at Roger Williams University in Rhode Island. In the first few days, many larval fish have no eyes or mouth, but live on their yolk.

“When they finally form eyes or mouths, it’s so important to have created an environment where they can get their first bite of zooplankton so they can get a little stronger and keep growing,” Rhyne says. “That was kind of the magic of it all.”

Often that first bite is a critical part of the ocean food system that harbors its own mysteries: Called copepods, they are microscopic crustaceans that provide vital nutrients to larval fish and are critical to breeders around the world.

At the Tropical Aquaculture Laboratory at the University of Florida at Ruskin — where the blue tang “Dory” fish popularized by the movie Finding Nemo was first successfully farmed — associate professor Matt DiMaggio and his students worked on the production of copepods. . But even copepods have proved difficult to breed.

More than 10,000 miles away from the Florida lab, on the tropical north coast of Bali, Indonesia, famed fish breeder Wen-Ping Su walks among large concrete aquariums, his very own zooplankton recipe churned into a circular tank nearby.

Su said he has 10 different keys to success that he has been developing for nearly two decades. Those keys have enabled him to breed fish that no one else has, including the striped regal angelfish and the black-colored pinnatus batfish with an orange border.

VALUABLE SECRETS

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But when he asks Wen-Ping Su to share details, his answer comes quickly, crossing his hands to form an X in front of his big smile: “No.”

It’s the same sentiment echoed by Bowling, who pauses when asked to share the secrets of his most high-profile successes. “That’s the part I really don’t want to tell you,” he laughs.

Those secrets are their livelihood. The spotted anthias Bowling bred after the broken air conditioner is listed on his company’s website for $700. Su-bred fish are also sold online for hundreds of dollars.

But in the past five years, there have been a few organizations — such as Rising Tide Conservation, a nongovernmental organization dedicated to developing and promoting aquaculture — that have worked to promote information sharing, DiMaggio said.

“That helped speed up the number of species we’ve been able to breed in that time and also the variety of species,” he said, focusing on species such as wrasses, butterflyfish and thorn.

Rhyne’s research lab — which includes breeding toothy queen triggerfish and red-streaked yasha gobies — has been working to share its research with breeders as well.

But Rhyne and other breeders admit it’s unlikely that all aquarium fish will be reared in captivity, as some are just too hard, while others are so bountiful in nature.

And breeding a fish doesn’t guarantee it will make it or do well in the market, Rhyne said. Captive-farmed fish costs more, and experts in the seafood industry recognize that it will take time to convince consumers to pay more for it.

“How do we market aquaculture fish like we market organic food, you know, and demand that premium price?” said Andersen, of the Coral Reef Aquarium Fisheries Campaign. “The marketing is very important.”

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Associated Press video journalist Marshall Ritzel reported from Florida. Kathy Young contributed to this report from New York. Andi Jatmiko, Edna Tarigan and Tatan Syuflana contributed from Indonesia.

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Follow Victoria Milko on Twitter: @thevmilko

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.

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