The sailfin catfish is the most successful, abundant and widespread of the armored catfish species and is
found throughout central and south Florida. Frequent sightings indicate that a reproductive population exists
in the North Fork SLR.
Native to North Africa and the Middle East, blue tilapia were imported in 1961 and have become established
throughout central and south Florida. Tilapias compete with other native species that feed primarily on
plankton and small organisms living in or on bottom detritus.
Walking catfish are an opportunistic species that consume a wide variety of food items including small fishes,
aquatic insects, plant material, and detritus. Due to its ability to breath air, this species thrives in water
with little to no oxygen and is well-adapted to short-lived water bodies with muddy bottoms. Habitat
preferences tend to segregate individuals and reduce its overall effect on native species.
The South American brown hoplo can be found in a variety of freshwater habitats including muddy bottom and
slow moving rivers, streams, side channels, ponds, marshes and manmade waterways such as ditches and borrow
pits. The species feeds on benthic invertebrates and is capable of gulping air to survive in areas with low
dissolved oxygen and high hydrogen sulfide levels.
Grass carp has recently been discovered in the North Fork SLR. To reduce maintenance costs, local
municipalities stock retention and golf course ponds with sterile grass carp. These ponds may become
hydrologically connected to the preserve during heavy rain events. The fundamental threat that grass carp
present to the natural resources within the preserve includes their ability to consume massive amounts of
vegetation. Aquatic vegetation is sparse within the preserve and serves as habitat and reproductive grounds
for a variety of fish (e.g. opossum pipefish and gar).
The Mayan cichlid is native to the Atlantic waters off Central and South America. This species is now abundant
through Lake Okeechobee and the St. Lucie Canal and tolerates a wide salinity range and habitats including
canals and rivers. Mayan cichlids consume grass shrimp, small fish, snails and insects. Specimens from the
preserve have been caught on hook and line and photographed by recreational anglers.
The African cattle egret naturally expanded its range to Florida in the early 1940s. Cattle egret
feed primarily in terrestrial pastures with cattle. Their unique foraging behavior has eliminated
feeding competition with other native wading birds. The largest threat that the cattle egret
presents to native species is the competition for nesting materials and rookery space. Cattle
egret nest late in the year in Florida which reduces but does not eliminate the competition for
space with native wood stork, egrets and herons.
Brazilian pepper has displaced native vegetation along the altered shorelines of the North Fork (such as
mangroves and leather fern), Five Mile Creek and Ten Mile Creek. Removal of this species along the river has
been initiated by local state park staff. This is an intensive process that requires constant attention and