But they are bad enough. Like a few other aquatic species, they start out as males and turn into females, ensuring the survival of the species. In South Florida's mild climate, they reproduce all year. They protect their young more aggressively than do the native fish. Scientists have tried to remove eels from Florida waters with extreme prejudice.
Swamp eels seem undaunted by explosives, which kill by rupturing air bladders of normal fish.
Swamp eels poke their heads out of the water and breathe air. So far, no eels have been discovered within Everglades National Park. But they have been apprehended in nearby canals. In the spring, biologists will try to kill as many as possible in the canal closest to the park. Electrocution will be the weapon of choice.