Blue Tilapia

Diet and feeding

The FishTraits compilation records these diet categories for this species: algae or phytoplankton; aquatic or other vascular plants; detritus or unidentified plant material; invertebrates or larval fish. These are broad categories, not a claim that every individual consumes every example in a category.

Reported feeding positions include bottom feeding and surface or water-column feeding. The compilation combines published observations; diets can vary with age, locality, and available food.

Habitat preferences

Reported habitat associations include medium to large rivers, streams and small rivers, still-water habitats.

The source records associations with muck, clay or silt, sand, vegetation, organic debris, large woody material. An association indicates reported use, rather than an exclusive requirement.

Reproduction and parental care

The compilation reports a representative maturity age of 1 years. Its maturity field summarizes mean, median, or modal estimates, usually for females; male estimates can be used when female data are unavailable. It is not a fixed age at which every fish first breeds.

Batch or serial spawning has been reported somewhere in the species’ range. This does not establish the same spawning pattern for every population.

Recorded spawning months are Apr, May, Jun, Jul, Aug, Sep, Oct for the source’s reporting region (FL). This is a regional calendar, not a range-wide schedule.

Size and recorded longevity

FishTraits reports a maximum total length of 45.7 centimetres. Some entries use an estimated asymptotic length; this value should not be treated as a certified record catch.

Recorded longevity in the compilation is 6 years. Wild observations were preferred, but captive records were accepted where wild records were unavailable, and unspecified records were assumed wild. The value is not a guaranteed wild lifespan or an aquarium life expectancy.

Identification and appearance

Distinguishing characteristics, synonyms, photographs, keys, and discussion of hybrids were provided in Trewavas (1983); for identification also see Page and Burr (1991), and Skelton (1993). Illustrations and diagnoses of larval and small juveniles of introduced populations were given by McGowan (1988). Color photographs were presented in Axelrod et al. (1985) and Axelrod (1993). Many or most accounts of "Tilapia nilotica" in U.S. ponds probably refer to O. aureus, likely imported from Israel, before the two species were shown to be distinct (Trewavas 1983).

Blue Tilapia is closely related to, and often confused with, Nile Tilapia (O. niloticus). These two species can generally be distinguished by the following characteristics (Trewavas 1983):

Native range

Tropical and subtropical Africa, and Middle East. Native range includes Senegal, Niger, and many smaller drainages and lakes in Africa and Middle East (Trewavas 1983; Skelton 1993).

Introduction history

This species has been introduced through a combination of means, including stocking and experimental work by states and private companies (e.g., the electric power industry), and release by individuals seeking to use the species as a sport fish, as forage for warmwater predatory fish, as a food source, and as a means of aquatic plant control. Introductions and spread have resulted by way of escapes or releases from aquaculture facilities and experimental control areas, and from various other holding sites (e.g., zoological parks); through aquarium and bait bucket releases; and by intentional transport by anglers and private individuals (Courtenay and Hensley 1979a; Lee et al. 1980 et seq.; Courtenay et al. 1984, 1986; Muoneke 1988; Courtenay and Williams 1992). The exact reasons for and sources of some introductions are uncertain (e.g., Texas) (Hubbs et al. 1978; Courtenay and Hensley 1979a). Apparently, power companies became interested in using so-called "tropical fishes" for food or sport in heated effluent ponds used to cool effluents from both fossil fuel fired and nuclear generating plants, where temperatures often became too high to support populations of native fishes (Courtenay and Hensley 1979a). Blue tilapia and redbelly tilapia were inadvertently introduced into Hyco Reservoir in North Carolina in 1984 after a small number of fish escaped from a holding cage located in the heated discharge area during an on-site agricultural study (Crutchfield 1995).

Ecological impacts

Blue tilapia have also been implicated as the cause for unionid mussel declines in two Texas water bodies, Tradinghouse Creek and Fairfield reservoirs (Howells 1995).