Gulf killifish
Gulf killifish, scientifically known as *Fundulus grandis*, are small fish typically found in grassy bays, canals, and freshwater bodies near the Atlantic Ocean and Gulf of Mexico, extending from northeastern Florida to Key West and northern Cuba. They generally measure between four and seven inches (10 to 18 centimeters) in length and are characterized by their blunt heads, rounded backs, and mottled scales—dark on the back and yellow on the belly, adorned with pale spots and bars. These fish are equipped with various fins that aid in their swimming, including dorsal, anal, pectoral, pelvic, and rounded caudal fins. As omnivores, Gulf killifish feed on a diverse diet of insects, small crustaceans, mollusks, worms, and algae. They are also preyed upon by larger sport fish like flounder and trout, and are often used as bait by fishermen. While their reproductive habits are not fully understood, they are believed to be egg-layers, with males displaying bright orange-yellow coloration during mating. Gulf killifish have a lifespan of up to two years, but they face threats from climate change and environmental disasters such as oil spills, which impact their habitats.
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Gulf killifish
Gulf killifish usually inhabit grassy bays, canals, and freshwater bodies which are near to the waters of the Atlantic Ocean and the Gulf of Mexico. Although Gulf killifish are named for inhabiting the Gulf of Mexico, they are not they only killifish to live in that region.
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cyprinodontiformes
Family: Fundulidae
Genus: Fundulus
Species: Grandis
Gulf killifish generally grow to a length of between four and seven inches (10 and 18 centimeters). They have blunt heads and rounded backs. Their elongated bodies are covered with dark scales on their backs and yellow scales on their bellies. All of these scales are mottled with small pale spots and bars.
Gulf killifish have a number of fins which help them move their rounded bodies through water. Along their backs, Gulf killifish each have a single dorsal fin. These fins work along with the anal fins on the fish's bellies to keep them balanced as they swim. For tails, Gulf killifish have rounded caudal fins. These fins move from side to side to propel Gulf killifish through the water. Gulf killifish also have pectoral and pelvic fins which help them paddle while they are swimming. The pectoral fins are located on either side of the fish's heads, while the pelvic fins are located along the fish's bellies.
Like other killifish, Gulf killifish need oxygen to live. Since they do not have lungs and cannot process oxygen from the air, like humans, they have to get the oxygen they need from the water in which they live. Gulf killifish take water into their mouths, keep the oxygen they need, and filter the waste chemicals out through the gills on the sides of their heads.
Gulf killifish inhabit the waters from northeastern Florida to Key West and from the northern Gulf of Mexico to Cuba. While these fish are typically found in grassy bays, canals, and throughout nearby freshwater bodies, they usually avoid tidal flats.
As omnivorous, or meat-and-plant-eating, fish, Gulf killifish feed on a variety of aquatic, or water-living, life-forms including insects, small crustaceans, mollusks, worms, and plant matter like algae.
Like other killifish, Gulf killifish are preyed upon by many larger, more aggressive sport fish, including flounder and trout. They may also be used by fishermen as bait to catch larger fish.
It is not known exactly how Gulf killifish reproduce, but they are believed to be an egg-laying species. Egg-laying means they go through the process of releasing and fertilizing eggs known as spawning.
It is most likely that Gulf killifish are egg-laying fish based on their size and surroundings and the mating habits of similar fish. During mating season, male Gulf killifish are known for their bright coloring. Their bodies turn a bright orange-yellow, while their cheeks remain dark black.
The life span of Gulf killifish is up to two years. While the Gulf killifish is not a threatened species, climate change, which has altered the salinity (salt content) and temperature of water, are threats to the species. Catastrophic events like the Deepwater Horizon oil spill also threaten the Gulf killifish.
Bibliography
“Gulf Killifish – Discover Fishes.” Florida Museum, 19 Aug. 2022, www.floridamuseum.ufl.edu/discover-fish/florida-fishes-gallery/gulf-killifish. Accessed 5 Apr. 2024.
Smithsonian Institution. “Species: Fundulus Grandis, Gulf Killifish.” Shorefishes - The Fishes, 2023, biogeodb.stri.si.edu/caribbean/en/thefishes/species/3262. Accessed 5 Apr. 2024.