They came. They saw. They ate.

They have not conquered yet, but triploid grass carp are catching on.

The Mongolian fish are becoming more popular as a method of controlling the weeds that clog many South Florida waterways.

The use of the fish in South Florida increased 83 percent from 1987 to 1988, state records show. At least 140 grass carp were put into Broward and Dade waterways last week.

The weed-eating fish will reduce, but not eliminate, the need for chemical herbicides, said Dave Eggeman, a state fisheries biologist. “We’d much rather see fish used if possible.”

Private firms such as Aqualogics Inc. of Pompano Beach are getting into the weed-eating carp business by supplying the suddenly popular species, Eggeman said.

“It’s definitely going to contribute to weed control in the future,” said Aqualogics’ John Fernandes. “It’s going to be a big thing.”

Fernandes’ latest batch arrived on a bus Friday night to munch on the weeds in the ponds at the Crystal Lake Country Club near Pompano Beach.

Five years ago, a 21-year-old scuba diver drowned in Crystal Lake after disappearing into a tangle of vegetation.

Since 1983, the state has issued 2,000 permits for stocking triploid grass carp, Eggeman said. Palm Beach County ranked No. 1 in use of the fish in the state last year.

Picture a pond set up like a cafeteria, in which the grass carp, also called amur, would go directly to the hydrilla, which is a weed, said Tom Latta, president of Ameraquatic, a Deerfield Beach firm that also raises and uses the fish for weed control.

“Duckweed and hydrilla would be like coconut custard pie for an amur,” Latta said. “They really go for those.”

The Boynton Beach Golf Course is happy with its hungry carp.

“There are water maintenance companies that can’t do as good as these fish,” superintendent Dan Miller said. “It’s safer than hiring a lake maintenance company to spray your lakes. I think it’s a lot better for your environment. It’s much more cost efficient.”

Miller said the fish keep the ponds free of weeds and even eat the clippings from the greens and fairways.

“They eat a lot,” Miller said. “You throw grass clippings in the lakes, and you see these hungry little mouths.”

They can eat too much, though, and not leave vegetation for other fish, state fisheries biologists said. That is why the state strictly controls how many fish are used and how they are used through permits.

“The biggest drawback, and that’s the reason why they are restricted, is that they will eat about anything that’s green that’s in the water,” said Mark Reed, a state fisheries biologist.

The fish must only be used where they are fenced in and cannot go to another lake, canal or pond.

The fish eggs are genetically altered to make the hatchlings sterile.

But even though they cannot reproduce, triploid grass carp are increasing in South Florida. They are shipped in from central Florida and Arkansas farms to be used in waterways, especially in new developments.

The latest variety of the fish have only been around six years. In 1987, the state issued 23 permits for their use in Palm Beach County. Last year, 78 permits were issued for the county.

“The big developments going on in Palm Beach County just west of I-95 … almost every one of them is putting in grass carp,” Eggeman said.

But in Broward County the number of permits dropped from 22 in 1987 to 10 last year.

Latta said that the fish were promoted too aggressively.

“I think the fish had a reasonable chance, but they had a hell of a fine press agent,” Latta said. “Expectations were very high, but then the reality caught up.”

“When you put in the fish, it’s not predictable,” Latta said. He said that about 25 percent of the time the fish work perfectly, 25 percent of the time they do not work much at all, and the rest of the time they are adequate.

WEED EATERS

NAME: Triploid grass carp

ORIGIN: Hybrids of diploid grass carp found in the Amur River in Mongolia. Latest variety was developed about six years ago.

APPEARANCE: They look like large brown and black goldfish, “big and ugly,” said John Fernandes, a weed control specialist.

WEIGHT: They can weigh up to 30 pounds and live 15 years.

BREEDING: As eggs, the fish are genetically altered by use of pressure so the fish have three sets of chromosomes instead of two. That makes them sterile.

TASTE: “They’re delicious,” said John Dequine, a Leesburg distributor of the fish. They are a staple of the east European diet, he said.