Class Osteichthyes (Bony Fish) in the Christopher B. Smith Preserve

Class Osteichthyes Characteristics: Osteichthyes is a taxonomic group consisting of over 435 families and 28,000 species. Bony fish are ectothermic (cold blooded), which makes their body temperature dependent on the temperature of the water in which they live. All bony fish have gills that are used for respiration, and an operculum that helps them breath without having to swim. Swim bladders help them maintain neutral buoyancy. They have smooth and overlapping scales, and mucus glands that coat the body.

In the Christopher B. Smith Preserve pond, five native species and four non native species have been netted and photographed.

Interactions in the Smith Preserve: Fish have many important functions in the preserve. They interact with their physical, chemical and biological environment. They are an integral part of the aquatic food web, eating plant life, microscopic organisms, other smaller fish, insects, crustaceans, worms, and amphibians, and they are prey for larger fish, birds, reptiles, and mammals.

Family Centrachidae

Family Cichlidae

 

Cichlasoma urophthalmus Mayan Cichlid In mid February 2018, the three Mayan cichlids shown here were netted in the Smith Preserve pond by Conservancy staff members. Both adult and juvenile Mayan cichlids have a yellow to olive-brown body, with 6 to 8 faint or dark vertical bars and a broken lateral line. The body color varies in intensity, sometimes with bright red on the chin (fish 2), throat, and breast. They have both spiny and soft dorsal fins and a rounded caudal fin. Many have a prominent dark ocellus (eyelike colored spot) ringed by blue at the base of the caudal fin. In Fish 1, this is a turquoise ring. Adult size is 22 cm. Mayan cichlids are native to the Atlantic slope of Central and South America. In Florida, they are considered non-native invasives. The species was first recorded in Everglades National Park in Florida Bay in 1983. The origin and date of the actual introduction to Florida is unknown, but it was probably due to aquarium releases or fish-farm escapes. Now the species is found in south Florida as far north as Lake Okeechobee and the St. Lucie Canal. These fishes live in canals, rivers, lakes and marshes and can tolerate a wide range of salinities. They usually spawn once a year following nest building. When young hatch from their eggs, they swim toward the bottom and attach to the substrate with adhesive head glands. They begin free-swimming in 5 to 6 days. Both parents guard young for about 6 weeks. Mayan cichlid food probably includes grass shrimp, small fish, snails, insects, detritus, and plant materials. According to the USGS website titled NAS- Nonindigenous Aquatic Species, "Studies have shown native fish population reductions when Mayan cichlids increase in number, possibly through competition pressures for food and space (Trexler et al. 2000), or alternatively through predation effects (Ferriter et al. 2006; Porter-Whitaker et al. 2012). Trexler et al (2000) also report anecdotal evidence of nest predation and competitive interactions for space with other substrate-spawning natives (centrarchids)." Although Mayan cichlids may compete for food and space with native fish populations, this assumption needs further study. A study of the stomach contents of locally-captured Mayan cichlids is being conducted by Conservancy scientist Dr. Jeff Schmid and science volunteer Copley Smoak to study food competition with native fish. Mayan cichlids are a source of good, quality meat for people. The meat is white and flaky with mild flavor. Return to top

 

 

Oreochromis aureus Blue Tilapia The first four photographs show a blue tilapia caught in mid February 2018 in the Smith Preserve pond by Conservancy science staff members (Melinda Schuman and Ian Bartoszek) and their daughter, Ursula. Blue tilapia are not native to Florida. They are native to Northern and Western Africa and the Middle East. The fish species is presently established in Florida, Texas, Alabama, Nevada and probably several other states. It is a freshwater fish with a high tolerance for brackish water that lives in fertile lakes, ponds, rivers, streams, and canals. It is considered the most widespread foreign fish species in Florida. The species may have been introduced as a food fish and to control aquatic vegetation. An adult, like the one shown in the first three photographs, is gray, shading to white on the belly. The borders of the dorsal and caudal fins have red to pink borders. The lateral line is broken and the spiny dorsal fin is joined to the soft dorsal fin. Adults are 13 to 20 cm in length and the fish can weigh 2.3 to 2.7 kg. Juveniles like the one directly above and the two below, captured on a different day in February 2018, are gray, sometimes with a black spot at the rear of the dorsal fin. Oreochromis aureus has been identified as an invasive species by Florida's Fish and Wildlife Commission. The species causes significant environmental damage because it competes with native species for spawning areas, food, and space. This species is primarily herbivorous, eating diatoms, green algae, and small organisms that live in bottom detritus. Juveniles eat small invertebrates. Spawning occurs when adult males dig large circular nests with their mouths in shallow water on sandy bottoms. Males stay near the nests and fertilize approaching females. Females lay eggs and as soon as they are fertilized, they take the eggs into their mouths and swim off to breed with other males. This egg-storing behavior characterizes them as "mouth brooders." After eggs hatch, young fry swim out to feed, but when threatened return to the mother's mouth until they are about 3 weeks old. Broods range from 160 to 1600 eggs per female. Return to top

 

 

Pelmatolapia mariae / Tilapia mariae Spotted Tilapia / Black Mangrove Cichlid This species is native to fresh and brackish wetlands in West and Central Africa, but this spotted tilapia was netted by Conservancy science staff in the Smith Preserve pond in mid February 2018. The first record of this fish species living in Florida waters was from south Miami-Dade County in April 1974. Introduction was probably from aquarium releases and fish farms. Today, it is considered established in canals, lakes, and ponds in at least eight Florida counties including Collier. It is the dominant fish in many canal systems in southeastern Florida. Spotted tilapia are considered non-native, invasive fish in Florida. Because this species has a high reproductive rate, simple food requirements, and tolerance to extremes in water temperature, salinity, and pollution, it rapidly populates its habitat, where it is aggressive and territorial. In Florida, possession and transport of a living spotted tilapia is illegal without a special permit. The species is considered a prohibited nonnative species in Florida (68-5.003, Florida Administrative Code). By definition a prohibited nonnative species is considered to be dangerous to the ecology and/or the health and welfare of the people of Florida. In this case it is dangerous to the ecology. Tilapia are an edible fish, raised for human consumption. Spotted tilapia have a short rounded snout and three anal spines. Color is dark olive green to light yellow. They have 8 or nine dark bars on their sides which are more evident in younger fish. These fish also have 2 to 6 dark spots between the bars on the middle of their side, which can be seen in this older specimen caught in the Smith Preserve pond. Spotted tilapia grow quickly and mature quickly, spending their lives at the bottom of the water eating mostly algae, diatoms, detritus, and aquatic plants. Adults reach a maximum of 32.2 cm. They breed year round and lay up to 2000 sticky eggs on submerged logs, rocks or plants. Parents are monogamous (ie. mate with only one partner at a time), and both parents help care for the young.   Return to top

 

Family Pocciliidae

© Photographs and text by Susan Leach Snyder (Conservancy of Southwest Florida Volunteer), unless otherwise credited above.

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