Animal Spotlight: The Lowdown on Lookdowns

For this Maryland native species, the Aquarium's Assateague Beach habitat is like a kiddie pool while it's adult swim over in the Atlantic Coral Reef exhibit.

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Lookdowns—flat, iridescent silver fish—are one of the species on exhibit in the Assateague Beach habitat in Maryland: Mountains to the Sea. This species inhabits the Atlantic Ocean as far north as Maine and as far south as Argentina. It's native to Maryland's coastal waters and the Chesapeake Bay.

Because the Assateague Beach habitat is small, and because lookdowns can grow to be more than a foot long, Curator Jay Bradley says juveniles are the best fit for the exhibit. Jay and his team recently added a new batch of babies to the habitat. These new additions currently measure less than 4 inches long.

"They're already losing some of their juvenile characteristics," Jay said, "but they still look a bit different than the adults. They have long, filament-like fins and yellowish coloration, which can help them hide among seagrasses."

To see adult lookdowns, look no further than another Aquarium habitat, Atlantic Coral Reef. Typically, a small school of three to five lookdowns cruise through the exhibit together, recognizable by their bright, shiny silver color along with the sharp slope of their faces and their slightly open, downturned mouths. They sometimes swim together in a fast, straight line, looking like they're in a hurry to get somewhere, rather than zig-zagging or meandering around like some other fish do.

Nurturing Fish Through Their Life Cycle

The juvenile lookdowns in Assateague Beach came to the Aquarium through an innovative new Association of Zoos and Aquariums (AZA) program that focuses on rearing larval fish.

Most fish have five stages in their life cycle—from an egg, they develop into a larva, then a fry, then a juvenile. From there, they grow into an adult.

"Sustainability is top of mind for the Aquarium and other AZA-accredited institutions," Jay said, "and this program is a way for different organizations to share resources and expertise, which benefits wild populations."

A Lookdown Fish With a Flattened Face and Open Mouth Swims Upward Against a Deep Blue Background.

Through the program, the lookdowns in Assateague Beach came to the National Aquarium from another AZA-accredited aquarium. A year from now, when the fish are starting to grow too large for the habitat, they will move to a different AZA aquarium that can accommodate an influx of larger lookdowns. At the same time, a new batch of juveniles will arrive in Baltimore, ready to go on exhibit.

"We also have smallmouth grunts and glassy sweepers in Atlantic Coral Reef from this program," Jay said. "We've started rearing neon gobies for Atlantic Coral Reef and Surviving Through Adaptation in a lab at the Animal Care and Rescue Center, and our hope is to really fine-tune our neon goby rearing system this year so we can start providing this species to other AZA institutions in the future."

Having different organizations specialize in the care of specific species of larval fish is more efficient and effective.

"Some species readily breed and lay eggs in Aquarium habitats," Jay explained. "When that happens, our team of aquarists gather up the eggs and, after they hatch, rear the fish through their larval phase. This requires an incredible amount of knowledge and work."

He continued, "There are 20,000 species of fish in the world, and we have nearly 400 species here. The process for raising each one from the larval stage is individual and different. Larvae need the right foods available to them at each stage of their development—"right" as in appropriate size, nutrition and location in the water column. It takes a long time to really understand each species' individual needs."

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