Also Known As: Peacock Flounder, Plate Fish

Compatibility and Behavior
The Tropical Flounder is a master of disguise, and watching one work is the whole appeal. This is a laterally compressed flatfish that lies on its side on the bottom, with both eyes migrated to the upward-facing side and a continuous fringe of dorsal and anal fins that ripples along its outline. Coloration varies by species, from sandy tan and mottled brown to olive-gray, often decorated with irregular blotching. What sets it apart is genuinely active camouflage: it can shift its pigmentation within seconds to match the tone and pattern of whatever it's resting on, then flick sand over itself until only the eyes protrude, each swiveling independently to scan for prey. It spends most of its time settled on the sand, moving in short undulating bursts across open bottom before settling again. It's peaceful toward tankmates of similar or larger size and ignores corals entirely, but make no mistake, it's an ambush predator and not reef safe, and it will likely eat ornamental shrimp, small crabs, snails, and any fish small enough to fit in its mouth. It pairs best with calm, appropriately sized fish up in the mid and upper water column, while aggressive fin-nippers, boisterous triggers, and puffers are best avoided, since they'll harass a resting flatfish or outcompete it at feeding time. It can also get territorial toward other bottom dwellers competing for sand space, so don't stock multiple flounders or sand-sifting gobies in a modest footprint.

Aquarium Requirements
Since this fish lives on the bottom, sand area matters far more than water volume. The small to medium specimens usually available settle in nicely in a 55 to 75 gallon tank, but they grow steadily and larger individuals want 125 gallons or more with a broad footprint, so prioritize a long, wide tank over a tall one. The single most important element of the setup is a deep bed of soft, fine sand across the entire bottom, since flounders bury themselves and coarse or angular substrate will abrade the delicate underside and blind side of the body. Keep aquascaping sparse and pushed toward the back, leaving generous open sand for the fish to reposition and hunt, and provide gentle to moderate, well-distributed flow rather than direct blasting jets. Softer lighting is appreciated, and a new arrival often stays buried and inconspicuous for the first several days, so don't panic when it disappears. Because flounders are strictly bottom feeders that may not rise for food, deliver meals directly to the sand near the fish, ideally after lights dim, and offering live grass shrimp or blackworms is often the most reliable way to establish a feeding response before transitioning to frozen fare.

Specifications
Approximate Size: Sm/Md: 1–2.5", Lg: 2.5–4"
Diet: Carnivore; chopped fresh or frozen marine meats including shrimp, squid, clam, krill, mysis, and marine fish flesh, with live grass shrimp or worms useful for initial feeding, delivered to the sand bed 3–4 times weekly
Origin: Indo-Pacific and Western Atlantic
Care Level: Moderate to expert
Reef Safe: No
Temperament: Peaceful toward appropriately sized tankmates, but an ambush predator toward anything small enough to swallow
Minimum Tank Size: 55 gallons for small specimens, with 125 gallons or more required as it grows
Special Considerations: Not reef safe and an ambush predator that will eat any shrimp, crab, snail, or fish small enough to swallow. Requires a deep bed of soft, fine sand, since coarse substrate abrades its delicate underside.